diff --git a/__tests__/utils/variables.test.ts b/__tests__/utils/variables.test.ts
index b684fb3..222819c 100644
--- a/__tests__/utils/variables.test.ts
+++ b/__tests__/utils/variables.test.ts
@@ -202,15 +202,15 @@ describe('getPrBranchName', () => {
     }))).toBe('test-ref');
   });
 
-  it('should throw error', async() => {
-    await expect(getPrBranchName(helper, octokit, generateActionContext({}))).rejects.toThrow();
-    await expect(getPrBranchName(helper, octokit, generateActionContext({}, {}, {prBranchName: ''}))).rejects.toThrow();
+  it('should get run number', async() => {
+    expect(await getPrBranchName(helper, octokit, generateActionContext({}), true)).toBe('1');
   });
 
   it('should throw error', async() => {
     await expect(getPrBranchName(helper, octokit, generateActionContext({event: 'pull_request'}, {}, {
       prBranchName: '${PR_NUMBER}::${PR_NUMBER_REF}::${PR_ID}::${PR_HEAD_REF}::${PR_BASE_REF}::${PR_TITLE}::${PR_URL}::${PR_MERGE_REF}::${PATCH_VERSION}::${MINOR_VERSION}::${MAJOR_VERSION}::${CURRENT_VERSION}::${PR_LINK}',
     }))).rejects.toThrow();
+    await expect(getPrBranchName(helper, octokit, generateActionContext({}))).rejects.toThrow();
   });
 });
 
diff --git a/src/utils/misc.ts b/src/utils/misc.ts
index 48058ed..470090c 100644
--- a/src/utils/misc.ts
+++ b/src/utils/misc.ts
@@ -11,13 +11,27 @@ const {getWorkspace, getPrefixRegExp, getAccessToken}                     = Util
 const {escapeRegExp, replaceAll, getBranch}                               = Utils;
 const {isPr, isCron, isPush, isCustomEvent, isManualEvent, isWorkflowRun} = ContextHelper;
 
+/**
+ * ParameterRequiredError
+ */
+export class ParameterRequiredError extends Error {
+  /**
+   * @param {string} target target
+   */
+  constructor(target: string) {
+    super(`parameter [${target}] is required.`);
+
+    Object.setPrototypeOf(this, ParameterRequiredError.prototype);
+  }
+}
+
 export const getActionDetail = <T>(key: string, context: ActionContext, defaultValue?: () => T): T => {
   if (undefined === defaultValue && !(key in context.actionDetail)) {
-    throw new Error(`parameter [${key}] is required.`);
+    throw new ParameterRequiredError(key);
   }
 
   if (undefined === defaultValue && typeof context.actionDetail[key] === 'string' && context.actionDetail[key].trim() === '') {
-    throw new Error(`parameter [${key}] is required.`);
+    throw new ParameterRequiredError(key);
   }
 
   return context.actionDetail[key] || (typeof defaultValue === 'function' ? defaultValue() : undefined);
diff --git a/src/utils/process.ts b/src/utils/process.ts
index d674b4c..55dd4e4 100644
--- a/src/utils/process.ts
+++ b/src/utils/process.ts
@@ -314,7 +314,7 @@ const runCreatePr = async(isClose: boolean, getPulls: (Octokit, ActionContext) =
     }
 
     const helper = getHelper(actionContext);
-    const target = context.actionDetail.prBranchName ? await getPrBranchName(helper, octokit, actionContext) : actionContext.actionContext.payload.number;
+    const target = await getPrBranchName(helper, octokit, actionContext, true);
     if (target in processed) {
       results.push(getResult('skipped', `duplicated (${target})`, actionContext));
       continue;
diff --git a/src/utils/variables.ts b/src/utils/variables.ts
index df947f6..d80196c 100644
--- a/src/utils/variables.ts
+++ b/src/utils/variables.ts
@@ -16,6 +16,7 @@ import {
   getPrBranchPrefix,
   getPrBranchPrefixForDefaultBranch,
   isNotCreatePR,
+  ParameterRequiredError,
 } from './misc';
 
 const {getBranch} = Utils;
@@ -96,16 +97,38 @@ const contextVariables = async(isComment: boolean, helper: GitHelper, octokit: O
  */
 const replaceContextVariables = async(string: string, helper: GitHelper, octokit: Octokit, context: ActionContext): Promise<string> => Utils.replaceVariables(string, await contextVariables(false, helper, octokit, context));
 
-export const getPrBranchName = async(helper: GitHelper, octokit: Octokit, context: ActionContext): Promise<string> =>
-  isPush(context.actionContext) ?
-    getBranch(context.actionContext) :
-    (
-      isActionPr(context) || isNotCreatePR(context) ? getPrHeadRef(context) : (
-        await isDefaultBranch(octokit, context) ?
-          getPrBranchPrefixForDefaultBranch(context) + await replaceContextVariables(getActionDetail<string>('prBranchNameForDefaultBranch', context, () => getActionDetail<string>('prBranchName', context)), helper, octokit, context) :
-          getPrBranchPrefix(context) + await replaceContextVariables(getActionDetail<string>('prBranchName', context), helper, octokit, context)
-      )
-    );
+export const getPrBranchName = async(helper: GitHelper, octokit: Octokit, context: ActionContext, isDuplicateCheck = false): Promise<string> => {
+  if (isPush(context.actionContext)) {
+    return getBranch(context.actionContext);
+  }
+
+  if (isActionPr(context) || isNotCreatePR(context)) {
+    return getPrHeadRef(context);
+  }
+
+  let prefix: string, branch: string;
+  if (await isDefaultBranch(octokit, context)) {
+    prefix = getPrBranchPrefixForDefaultBranch(context);
+  } else {
+    prefix = getPrBranchPrefix(context);
+  }
+
+  try {
+    if (await isDefaultBranch(octokit, context)) {
+      branch = getActionDetail<string>('prBranchNameForDefaultBranch', context, () => getActionDetail<string>('prBranchName', context));
+    } else {
+      branch = getActionDetail<string>('prBranchName', context);
+    }
+  } catch (error) {
+    if (isDuplicateCheck && (error instanceof ParameterRequiredError)) {
+      return `${context.actionContext.runNumber}`;
+    }
+
+    throw error;
+  }
+
+  return prefix + await replaceContextVariables(branch, helper, octokit, context);
+};
 
 export const getPrTitle = async(helper: GitHelper, octokit: Octokit, context: ActionContext): Promise<string> => await replaceContextVariables(
   (