A temperature-detecting device includes a frame, a temperature-detecting unit, a driving unit, a rotation-controlling unit, and a controller. The temperature-detecting unit includes a sensor, a sensor cap, and a sensor case. The rotation-controlling unit is configured to stop rotation of the sensor cap when the temperature-detecting unit reaches a target angle that is over 360 degrees from a reference position, with the sensor case being kept rotated by the driving unit such that the sensor is displaced from an opening and is covered by the sensor case. The controller is configured to correct a temperature detected while the sensor is exposed at the opening, with reference to a temperature detected while the sensor is covered by the sensor case.