PURPOSE: To make it possible to produce the capacity of a power source and also to increase driving speed, etc., by employing such a design as to divide heat-generating resistors for one line into blocks and to conduct drive control of all the head driving circuits by a common head control circuit.

CONSTITUTION: The driving device is designed in such a manner that all the heat- generating resistors H1WHn for one line are divided into blocks, and drive controls of head driving circuits DV1WDVm having been thus divided into blocks are conducted by a common head controlling circuit. Whether or not "1" information exists in input signals sent into these blocks is detected by said head controlling circuit and the result is also stored by said circuit, and in case where an image information is "1", a heat-generating resistor corresponding to the image is made to generate heat in a sufficient time, and when the image information is "0" it is controlled not to consume time, so that the power as a whole is averaged and a constant power driving is achieved.