In an image forming apparatus that receives print data from an external device and prints out the print data in response to a print command, a searching unit that searches, when new print data is received from the external device, a storage unit storing therein the print data that includes user information for previous print data that includes user information same as that of the new print data; and a notifying unit that sends, when the searching unit finds the previous print data, a notice to the external device saying that the previous print data is still present in the storage unit.