An image forming device that forms an image on a medium, includes: a heater that heats the medium; a control unit that controls the heater; a first path that receives input voltage from an external power supply, converts the input voltage into desired voltage, and supplies the desired voltage to the control unit; a second path that divides the input voltage received by the first path and supplies the input voltage to the heater; a control element that is connected to the second path and controls ON/OFF switching of the heater according to control from the control unit; and a disconnection unit that disconnects the second path depending on condition of the input voltage.