diff --git a/src/modules/commands/bundling.ts b/src/modules/commands/bundling.ts
index ba79cd8..d3cbc6f 100644
--- a/src/modules/commands/bundling.ts
+++ b/src/modules/commands/bundling.ts
@@ -16,9 +16,7 @@ import { ProjectContainer } from '#/modules/file/ProjectContainer';
 import { checkOutputFile } from '#/modules/file/checkOutputFile';
 import { getTsExcludeFiles } from '#/modules/file/getTsExcludeFiles';
 import { getTsIncludeFiles } from '#/modules/file/getTsIncludeFiles';
-import { addCurrentDirPrefix } from '#/modules/path/addCurrentDirPrefix';
 import { posixJoin } from '#/modules/path/modules/posixJoin';
-import { posixRelative } from '#/modules/path/modules/posixRelative';
 import { posixResolve } from '#/modules/path/modules/posixResolve';
 import { ExcludeContainer } from '#/modules/scope/ExcludeContainer';
 import { IncludeContainer } from '#/modules/scope/IncludeContainer';
@@ -28,12 +26,11 @@ import { CE_TEMPLATE_NAME } from '#/templates/const-enum/CE_TEMPLATE_NAME';
 import type { IIndexFileWriteParams } from '#/templates/interfaces/IIndexFileWriteParams';
 import type { IIndexRenderData } from '#/templates/interfaces/IIndexRenderData';
 import { TemplateContainer } from '#/templates/modules/TemplateContainer';
+import { getInlineDeclarationRenderData } from '#/templates/modules/getInlineDeclarationRenderData';
 import { getRenderData } from '#/templates/modules/getRenderData';
 import { getSelectStyle } from '#/templates/modules/getSelectStyle';
 import chalk from 'chalk';
 import dayjs from 'dayjs';
-import { replaceSepToPosix } from 'my-node-fp';
-import path from 'node:path';
 import type * as tsm from 'ts-morph';
 
 export async function bundling(buildOptions: TCommandBuildOptions, bundleOption: TBundleOptions) {
@@ -194,30 +191,7 @@ export async function bundling(buildOptions: TCommandBuildOptions, bundleOption:
     CE_TEMPLATE_NAME.DECLARATION_FILE_TEMPLATE,
     {
       options: { quote: bundleOption.quote },
-      declarations: await Promise.all(
-        inlineDeclarations
-          .filter((inlineDeclaration) => statementMap.get(inlineDeclaration.filePath) == null)
-          .map((declaration) => {
-            const relativePath =
-              bundleOption.output != null
-                ? addCurrentDirPrefix(
-                    posixRelative(
-                      bundleOption.output,
-                      path.join(
-                        path.dirname(declaration.filePath),
-                        path.basename(declaration.filePath, path.extname(declaration.filePath)),
-                      ),
-                    ),
-                  )
-                : replaceSepToPosix(
-                    `.${path.posix.sep}${path.join(
-                      path.dirname(declaration.filePath),
-                      path.basename(declaration.filePath, path.extname(declaration.filePath)),
-                    )}`,
-                  );
-            return { ...declaration, relativePath };
-          }),
-      ),
+      declarations: getInlineDeclarationRenderData(inlineDeclarations, bundleOption),
     },
   );
 
diff --git a/src/templates/modules/__tests__/get.inline.declaration.render.data.test.ts b/src/templates/modules/__tests__/get.inline.declaration.render.data.test.ts
new file mode 100644
index 0000000..d368eb9
--- /dev/null
+++ b/src/templates/modules/__tests__/get.inline.declaration.render.data.test.ts
@@ -0,0 +1,112 @@
+import { CE_INLINE_COMMENT_KEYWORD } from '#/comments/const-enum/CE_INLINE_COMMENT_KEYWORD';
+import type { getInlineCommentedFiles } from '#/comments/getInlineCommentedFiles';
+import { getInlineDeclarationRenderData } from '#/templates/modules/getInlineDeclarationRenderData';
+import pathe from 'pathe';
+import { describe, expect, it } from 'vitest';
+
+describe('getInlineDeclarationRenderData', () => {
+  it('successfully generate render data, with output directory', () => {
+    const declarations: ReturnType<typeof getInlineCommentedFiles> = [
+      {
+        filePath: pathe.join(process.cwd(), '/a/b/c/d/a.ts'),
+        commentCode: `// ${CE_INLINE_COMMENT_KEYWORD.FILE_DECLARATION_KEYWORD}`,
+        tag: CE_INLINE_COMMENT_KEYWORD.FILE_DECLARATION_KEYWORD,
+        pos: {
+          line: 0,
+          column: 0,
+          start: 0,
+        },
+        workspaces: undefined,
+      },
+      {
+        filePath: pathe.join(process.cwd(), '/a/b/c/e/b.ts'),
+        commentCode: `// ${CE_INLINE_COMMENT_KEYWORD.FILE_DECLARATION_KEYWORD}`,
+        tag: CE_INLINE_COMMENT_KEYWORD.FILE_DECLARATION_KEYWORD,
+        pos: {
+          line: 0,
+          column: 0,
+          start: 0,
+        },
+        workspaces: undefined,
+      },
+    ];
+
+    const data = getInlineDeclarationRenderData(declarations, {
+      output: pathe.join(process.cwd(), '/a/b/e'),
+      fileExt: 'to-js',
+    });
+
+    expect(data).toMatchObject([
+      {
+        filePath: pathe.join(process.cwd(), '/a/b/c/d/a.ts'),
+        commentCode: '// @ctix-declaration',
+        tag: '@ctix-declaration',
+        pos: { line: 0, column: 0, start: 0 },
+        workspaces: undefined,
+        relativePath: '../c/d/a.ts',
+        extname: { origin: '.ts', render: '.js' },
+      },
+      {
+        filePath: pathe.join(process.cwd(), '/a/b/c/e/b.ts'),
+        commentCode: '// @ctix-declaration',
+        tag: '@ctix-declaration',
+        pos: { line: 0, column: 0, start: 0 },
+        workspaces: undefined,
+        relativePath: '../c/e/b.ts',
+        extname: { origin: '.ts', render: '.js' },
+      },
+    ]);
+  });
+
+  it('successfully generate render data, without output directory', () => {
+    const declarations: ReturnType<typeof getInlineCommentedFiles> = [
+      {
+        filePath: pathe.join(process.cwd(), '/a/b/c/d/a.ts'),
+        commentCode: `// ${CE_INLINE_COMMENT_KEYWORD.FILE_DECLARATION_KEYWORD}`,
+        tag: CE_INLINE_COMMENT_KEYWORD.FILE_DECLARATION_KEYWORD,
+        pos: {
+          line: 0,
+          column: 0,
+          start: 0,
+        },
+        workspaces: undefined,
+      },
+      {
+        filePath: pathe.join(process.cwd(), '/a/b/c/e/b.ts'),
+        commentCode: `// ${CE_INLINE_COMMENT_KEYWORD.FILE_DECLARATION_KEYWORD}`,
+        tag: CE_INLINE_COMMENT_KEYWORD.FILE_DECLARATION_KEYWORD,
+        pos: {
+          line: 0,
+          column: 0,
+          start: 0,
+        },
+        workspaces: undefined,
+      },
+    ];
+
+    const data = getInlineDeclarationRenderData(declarations, {
+      fileExt: 'to-js',
+    });
+
+    expect(data).toMatchObject([
+      {
+        filePath: pathe.join(process.cwd(), '/a/b/c/d/a.ts'),
+        commentCode: '// @ctix-declaration',
+        tag: '@ctix-declaration',
+        pos: { line: 0, column: 0, start: 0 },
+        workspaces: undefined,
+        relativePath: `./${pathe.join(process.cwd(), '/a/b/c/d/a.ts')}`,
+        extname: { origin: '.ts', render: '.js' },
+      },
+      {
+        filePath: pathe.join(process.cwd(), '/a/b/c/e/b.ts'),
+        commentCode: '// @ctix-declaration',
+        tag: '@ctix-declaration',
+        pos: { line: 0, column: 0, start: 0 },
+        workspaces: undefined,
+        relativePath: `./${pathe.join(process.cwd(), '/a/b/c/e/b.ts')}`,
+        extname: { origin: '.ts', render: '.js' },
+      },
+    ]);
+  });
+});
diff --git a/src/templates/modules/getInlineDeclarationRenderData.ts b/src/templates/modules/getInlineDeclarationRenderData.ts
new file mode 100644
index 0000000..c61988c
--- /dev/null
+++ b/src/templates/modules/getInlineDeclarationRenderData.ts
@@ -0,0 +1,40 @@
+import type { getInlineCommentedFiles } from '#/comments/getInlineCommentedFiles';
+import type { TBundleOptions } from '#/configs/interfaces/TBundleOptions';
+import { addCurrentDirPrefix } from '#/modules/path/addCurrentDirPrefix';
+import { getExtname } from '#/modules/path/getExtname';
+import { getImportStatementExtname } from '#/modules/path/getImportStatementExtname';
+import { posixRelative } from '#/modules/path/modules/posixRelative';
+import { replaceSepToPosix } from 'my-node-fp';
+import path from 'path';
+import pathe from 'pathe';
+import type { SetOptional } from 'type-fest';
+
+export function getInlineDeclarationRenderData(
+  declarations: ReturnType<typeof getInlineCommentedFiles>,
+  options: SetOptional<Pick<TBundleOptions, 'output' | 'fileExt'>, 'output'>,
+) {
+  const renderDatas = declarations.map((declaration) => {
+    const extname = getExtname(declaration.filePath);
+    const renderExtname = getImportStatementExtname(options.fileExt, extname);
+    const dirname = pathe.dirname(declaration.filePath);
+    const basename = pathe.basename(declaration.filePath, extname);
+
+    const relativePath =
+      options.output != null
+        ? addCurrentDirPrefix(
+            posixRelative(options.output, pathe.join(dirname, `${basename}${extname}`)),
+          )
+        : replaceSepToPosix(`.${path.posix.sep}${pathe.join(dirname, `${basename}${extname}`)}`);
+
+    return {
+      ...declaration,
+      relativePath,
+      extname: {
+        origin: extname,
+        render: renderExtname,
+      },
+    };
+  });
+
+  return renderDatas;
+}
diff --git a/src/templates/templates/declarationFileTemplate.ts b/src/templates/templates/declarationFileTemplate.ts
index 1c63d9b..25b444d 100644
--- a/src/templates/templates/declarationFileTemplate.ts
+++ b/src/templates/templates/declarationFileTemplate.ts
@@ -1,6 +1,6 @@
 export const declarationFileTemplate = `
 <%- it.declarations.forEach((declaration) => { -%>
-import <%-= it.options.quote %><%= declaration.relativePath %><%= it.options.quote -%>
+import <%-= it.options.quote %><%= declaration.relativePath %><%= declaration.extname.render %><%= it.options.quote -%>
 
 <%- }) %>
 `;