A printing apparatus includes a printing unit for performing printing by pressing a thermal head onto heat sensitive paper to heat the heat sensitive paper. A battery supplies a voltage to the thermal head, and a battery voltage detecting unit detects the voltage. A printing control unit changes, according to the detected voltage, a power-off time in which power supply from the battery to the thermal head is stopped. The printing control unit calculates the power-off time based on the detected voltage and the resistance of the thermal head and shortens the power-off time as the detected voltage becomes lower thereby shortening the overall printing time without shortening the life of the heating resistance elements of the thermal head.