The difference between internal processes of a power converting apparatus may bring about a heat difference in the apparatus. In the cooling process, it is presumed that the temperature change of the inverter or converter module may be made so great that the power converting apparatus may be less reliable. In order to overcome this shortcoming, the temperature of the internal module is measured and a cooling control of a cooling fan or the like is carried out on the measured result. This cooling control of the cooling fan causes the life of a switching element of the inverter or converter to be longer.