A level change point detection section detects a level change point, at which an output level switches, in a first position detection signal Ens1 generated by an encoder or a second position detection signal obtained by increasing the resolution of the Ens1. Each time a predetermined number of level change points is detected, an energization timing determination section determines the timing, at which the predetermined number of level change points have been detected, to be an energization timing for the thermal head.