According to one embodiment, a temperature detection circuit is provided which requires only a small number of additional components, thus minimizing an increase in costs and which offers an insulating property and high responsiveness. A temperature detection circuit outputs a first PWM signal corresponding to a temperature of a first temperature sensor from a photointerrupter as a signal insulated from the first temperature sensor. A temperature detection circuit outputs a second PWM signal corresponding to a temperature of a second temperature sensor from a photointerrupter as a signal insulated from the second temperature sensor. A controlling arithmetic apparatus calculates a higher one of the temperatures detected by the first and second temperature sensors based on the PWM signals output from the photointerrupter.