PURPOSE: To effectively shorten a warming up time and effectively prevent the deterioration of a head performance caused by cogging while reducing the head cost.

CONSTITUTION: Under a condition that a printing mode is selected by a mode selection means 4 selecting either a printing mode or a heating mode, an image control means 3 consists of the mode selection means 4 and a printing mode execution means 5 dividing a group of drive elements 2 into a plurality of blocks B and successively driving the blocks B. Under a condition that a heating mode is selected by the mode selection means 4, the image control means 3 consists of the mode selection means 4 and a heating mode execution means 6 simultaneously driving all the group of drive elements 2 while setting a supply voltage to heating elements 1 to be lower than that in a printing mode.