RANGING DEVICE

A ranging device is configured to emit a transmitted wave and detect a reflected wave from an object illuminated by the transmitted wave, thereby measuring a distance to the object. At least one of the transmitted wave and the reflected wave is transmitted through a transmission window. A heater is configured to heat the transmission window. A controller is configured to control energization of the heater in response to an outside temperature that is a temperature outside the ranging device and a speed of the vehicle.