PURPOSE: To speedily take a copy by holding the preheating temperature of a heat fixing device at a high value in a time zone wherein the frequency of use is high and to save the electric power used to preheat the heat fixing device in a time zone when the frequency of use is low.

CONSTITUTION: This copying machine has a power consumption setting means (M+E) which sets the power consumption of the heat fixing device 4 in a copy stand-by state of normal use mode. The normal use mode or a learning mode can be selected with a mode selecting means SW1. A use frequency storage means (M+Me) stores the frequency of use of the copying machine by the days of the week and time zones while the learning mode is selected. The power consumption setting means (M+E) sets the power consumption of the heat fixing device 4 lower on days of the week and in time zones wherein the frequency of use is low than on days of the week and in time zones wherein the frequency of use is high.