To minimize image data that are not transmitted even in the case that a decode error or power supply interruption takes place in an image transmitter.

On the occurrence of a decode error in an A/V decode section 1p, a system control section 1n informs a personal computer 2 about it, the personal computer 2 references a broadcast program to specify image data that are being reproduced, calculates a position at which reproduction of the image data is restarted on the basis of a reproduction start time, a current time and a time required to start reproduction processing and informs an image server 1 about the position. The image server 1 starts reproduction of the image data from the designated position of a concerned file stored in a hard disk drive HDD.