An image processing apparatus is disclosed connected to a multiple number of external devices by way of a LAN. The apparatus has a main board for expanding the image data received as a print job from one of the external devices and a sub board serving as a connecting port with the LAN. In the power saving mode, the apparatus supplies power to the sub board only, when cutting off power supply to the main board. A time-designated printing data storage stores the data therein when receiving time-designated printing data in the power saving mode. A time-designated printing data extractor extracts at least one set of time-designated printing data, in accord with predetermined conditions, from (i) the sets of time-designated printing data being stored in the time-designated printing data storage and (ii) a newly received set of time-designated printing data. A time-designated printing data forwarding portion transfers the time-designated printing data extracted at the time-designated printing data extractor to an external device that is different from the external device from which the image data was originally transmitted.