diff --git a/app/controllers/personal_books_controller.rb b/app/controllers/personal_books_controller.rb
index 488d562..85288a2 100644
--- a/app/controllers/personal_books_controller.rb
+++ b/app/controllers/personal_books_controller.rb
@@ -40,7 +40,7 @@ class PersonalBooksController < ApplicationController
          books_show = books_temp.select {|value| search_all_words(value.create_link, params[:keywords])}
         end
       when "publish_date", "publication_date"
-          books_show = books_temp.select {|value| search_all_words(value.send(params[:selectbox]).strftime("%Y/%m/%d").to_s, params[:keywords])}
+          books_show = books_temp.select {|value| search_all_words((value.send(params[:selectbox]).strftime("%Y/%m/%d") rescue ""), params[:keywords])}
       when "author_type"
           books_show = books_temp.select {|value| search_all_words(value.book_author_types.collect{|bat| bat.title}.join(", "), params[:keywords])}
       when "language"
@@ -70,7 +70,7 @@ class PersonalBooksController < ApplicationController
            t << {"value" => "<a href='#{OrbitHelper.url_to_show(book.to_param)}'>#{book.create_link}</a>"}
           end
         when "publish_date", "publication_date"
-          t << {"value" => (!book.send(fs).nil? ? book.send(fs).strftime('%Y/%m') : "")}
+          t << {"value" => (!book.send(fs).nil? ? book.send(fs).strftime('%Y/%m') : "" rescue "")}
         when "author_type"
           t << {"value" => (book.book_author_types.collect{|bat| bat.title}.join(", ") rescue "")}
         when "language"