PURPOSE: To provide a simple method for detecting the moisture content of a transfer material and to obtain the stable image with high image quality by controlling a transfer current considering the moisture content of the transfer material and each device.

CONSTITUTION: The current which an attracting current applied by an attracting corontron 66 disposed inside a transfer drum 60 at the time of attracting the transfer material 5 flows into a deflector roll 64 disposed correspondingly to the attracting corontron 66 through a transfer film 600 is measured by an ammeter 100 provided on mid-way of an earthed electric wire 110, and the moisture content is detected from the measured value. Then, the moisture content of the transfer material 5 is added to a bit of information and each device of an electrophotographic copying machine is controlled so that an excellent transfer image can be always obtained.