The present invention discloses a power conversion apparatus, which can inhibit the freezing of refrigerant even if the temperature of cooling wind is below a freezing point of the refrigerant inside a heat pipe, and can balance the influence of heat distribution change of semiconductor elements caused by different operation conditions or influence caused by temperature rising of the cooling wind, therefore cooling can be done effectively. The power conversion apparatus is characterized in that a plurality of semiconductor elements comprise a plurality of first IGBT modules that have enlarged heat volume in regenerative operation, a plurality of second IGBT modules that have enlarged heat volume in power operation, and a plurality of clamping diode modules that have smaller heat than the IGBT modules. Semiconductor elements that have same heat are arranged in an orthogonal direction with the flow of the cooling wind, and the clamping diode modules are set between the first IGBT modules and the second IGBT modules in the flow direction of the cooling wind.