PURPOSE: To afford a sufficient time to turn off a thyristor by asigning a printing command pulse from a pulse position converting unit to groups of switching elements in relation with counts of a counter to turn them ON for a certain time.

CONSTITUTION: This apparatus has an analog input pulse position converting unit 2, a counter unit 3 adapted to output action control signal thereto while scanning a record electrode, a decoder unit 4 for dicimary-coding the output thereof and a power switch unit 7 containing an OR circuit 6 for feeding the output of the unit 2 to a head driver unit 5 as pulse train. Record electrodes 8 are provided in parallel perpendicular to the direction of feeding a recording paper P. A latch circuit 11 is arranged to temporarily hold output values of an A/D converter 10 and a comparator circuit 12 to compare the output value with counts of the counter 3. A one shot multivibrator 13 adapted to work receiving this output is also provided. Thus, switching elements are turned ON for a certain time with the one shot multivibrator to extend the turn-off time of a thyrister thereby realizing a high-speed and high accuracy recording.