To provide an image forming apparatus that executes a printing operation in a condition that a clock signal or a driving current is lowered or reduced in a time band wherein a printing operation rate is low at a power saving mode and in a time-designated printing that does not require a high speed printing.

This image forming apparatus comprises a CPU 1, an ASIC 2, a clock generating section 3, a RAM 4, a ROM 5, an external device I/F control section 6, an operation section 7, a display section 8, an engine I/F control section 9, a storing section 10 and a sub-CPU 11. In this image forming apparatus, the printing is controlled in a condition that the clock frequency is lowered and the driving current is reduced in a print job that does not require a print performance such as the time-designated printing during the power saving mode so that the power consumption is reduced.