According to the invention, there is provided a water cooled inverter structure forming a plurality of shallow cavities and deep cavities in a housing, fixing a bottom surface of power semiconductor modules to shallow cavities to form a shallow water channel and directly cooling the power semiconductor modules using this shallow water channel. Since cooling water flows fast in the shallow water channel, it is possible to improve a cooling efficiency and also reduce pressure loss using a deep water channel with deep cavities. Furthermore, providing a plurality of cavities makes it possible to reduce a size of the power semiconductor modules and provide a plurality of power semiconductor modules, thus improving reliability. It is possible to place a control board below the water channel to thermally cut off the control board from the power semiconductor modules, which makes it possible to reduce temperature of a control circuit.