To provide an FPU device in which the internal temperature rise will be within allowable value, even when a fan for air cooling fails and which is free from instantaneous interruption.

The FPU device, to which a digital modulation system and an analog FM modulation system can be applied, is provided with an SHF output power switching means, a cooling fan for cooling the FPU device, and at least one of a means for detecting the stop of the cooling fan and a means for detecting the temperature inside the FPU device. The FPU device is such that, when the temperature inside the FPU device becomes a prescribed value or higher during a digital modulation system operation, the bias of a power amplifier is used as the bias for the lowered SHF output of the analog FM modulation system, and changeover to the level of the lowered SHF output is performed automatically.