The printer (1) includes a control unit (20) including a function reproducing multiple tones by outputting energization data that is dot control data in multiple cycles in line units to a head unit (10) including a plurality of dot generating elements disposed in a line. The control unit (20) includes: a thermal head control circuit (60) supplying the energization data of each cycle and a latch signal for the energization data of each cycle to the head unit (10); and a mask circuit (70) operable when the energization data of the current cycle is the same as the energization data of the previous cycle, to erase the current energization data and the signal for latching to be supplied to the head unit (10).