A printing device comprising: a printing part for printing ink on a printing medium, a first air heater part and a second air heater part for heating and drying the printed medium on which the ink is printed, and a control part that ON/OFF controls heating of the first air heater part and the second air heater part, wherein each of the first air heater part and the second air heater part is constituted by at least one or more air heaters, characterized in that each of the heaters is provided with a temperature detection part for measuring a current temperature when a first control starts, and that the control part includes the first control in which the first air heater part is turned ON, while the second air heater part is simultaneously turned OFF, and a second control in which the first air heater part is turned OFF, while the second air heater part is simultaneously turned ON, and a third control for turning OFF the corresponding air heater prior to the passage of a fixed period of time, based upon a temperature difference obtained by subtracting a target temperature from the current temperature of the air heater to be turned ON, with the first control and the second control being alternately switched in each fixed period, and wherein supposing that continuously heating for the fixed period of time is 100% duty cycle, in the case when the current temperature of the air heater to be turned ON in the third control is the same as the target temperature, after carrying out a heating process in an updated duty cycle updated to X1% duty cycle, the corresponding air heater is turned OFF, in the case when the current temperature of the air heater to be turned ON is higher than the target temperature, after carrying out a heating process in an updated duty cycle updated to X2% duty cycle, the corresponding air heater is turned OFF, and in the case when the current temperature of the air heater to be turned ON is lower than the target temperature, after carrying out a heating process in an updated cycle updated to X3% duty cycle, the corresponding air heater is turned OFF, and wherein said X1 is set to 20 to 30, and said X1, X2 and X3 satisfy a relational expression: X2 < X1 < X3. a printing part for printing ink on a printing medium, a first air heater part and a second air heater part for heating and drying the printed medium on which the ink is printed, and a control part that ON/OFF controls heating of the first air heater part and the second air heater part, wherein each of the first air heater part and the second air heater part is constituted by at least one or more air heaters, characterized in that each of the heaters is provided with a temperature detection part for measuring a current temperature when a first control starts, and that the control part includes the first control in which the first air heater part is turned ON, while the second air heater part is simultaneously turned OFF, and a second control in which the first air heater part is turned OFF, while the second air heater part is simultaneously turned ON, and a third control for turning OFF the corresponding air heater prior to the passage of a fixed period of time, based upon a temperature difference obtained by subtracting a target temperature from the current temperature of the air heater to be turned ON, with the first control and the second control being alternately switched in each fixed period, and wherein supposing that continuously heating for the fixed period of time is 100% duty cycle, in the case when the current temperature of the air heater to be turned ON in the third control is the same as the target temperature, after carrying out a heating process in an updated duty cycle updated to X1% duty cycle, the corresponding air heater is turned OFF, in the case when the current temperature of the air heater to be turned ON is higher than the target temperature, after carrying out a heating process in an updated duty cycle updated to X2% duty cycle, the corresponding air heater is turned OFF, and in the case when the current temperature of the air heater to be turned ON is lower than the target temperature, after carrying out a heating process in an updated cycle updated to X3% duty cycle, the corresponding air heater is turned OFF, and wherein said X1 is set to 20 to 30, and said X1, X2 and X3 satisfy a relational expression: X2 < X1 < X3.