Conventional power converter employs a circulation type coolers comprising a heat pipe or a pump in order to cool semiconductor elements and thereby requires many spaces for the coolers. The inventive power converter comprises semiconductor elements (7) performing switching for power conversion, a plurality of bubble pump type coolers (6) each having a element cooling section (6A) for cooling the semiconductor elements (7) with refrigerant and a heat radiating section (6C) for radiating heat from refrigerant heated at the element cooling section (6A) and circulating the refrigerant between the heat radiating section (6C) and the element cooling section (6A) by boiling the refrigerant at the element cooling section (6A), the heat radiating sections (6C) being stacked contiguously to each other, and a cooling fan (2) for generating air stream striking the heat radiating section (6C).