A camera is made compact with its internal temperature adjusted to a more appropriate temperature. A temperature T is read from a temperature sensor disposed within the camera (S100) and it is judged whether or not the temperature T exceeds a threshold Tref1 (S102). When the temperature T exceeds the threshold Tref1, the operation of the camera is changed to a power-saving mode where the power consumption is lower than in the ordinary mode (S104). The threshold Tref1 is determined to be a rated temperature at which the camera can operate stably or a temperature lower than that. Thus, the temperature in the camera can be made appropriate.