To reduce economical burden due to an output device or the burden of operator when simultaneously processing various kinds of image data from plural means for generating image data.

A lot of external image information generating means (such as PC 1 and PC 2) are connected to a main digital copy machine 1 so as to enable transmission/reception. A digital copy machine 1a as an output means (main output means) for outputting a hard copy and subordinate output means (1b, 53 and 52) are connected through a communication line 58 to the main digital copy machine 1 so as to transmit image data and further, FAX equipment as this image information generating means is connected through a telephone line 51. The digital copy machine 1 receives the image data from this image information generating means and when these data can be processed by itself, output processing is performed there. When these data can not be processed, any output means enabling processing is selected, the data are transferred to that means and control is performed so as to output the hard copy on the side of that output device.