In a system for file managing image data of an electronic camera, so long as the image data is recorded by the same image pickup apparatus, a peculiar file name which is not overlapped is generated and in order to prevent that a plurality of files of the same name exist, when an electronic camera is connected to a main body of a computer, a storage device in the electronic camera is examined from a host application of the computer, and when a file of a file name including numerical values exceeding a predetermined value is found, a message is displayed for the user in a manner such that after all of the files having the file names which had automatically been formed were transferred to the computer, all of the contents in the storage device are deleted or formatted. When the detachable storage device is loaded or a power source is turned on, if the file having the unique file name which was automatically generated does not exist in the storage device, the numerical values held in the electronic camera are initialized.