The present invention provides an electric power converter in which a tip portion of a cooling fin on an air flow inlet side is limited to flow a large quantity of air around a connection portion, where the fin efficiency is high, of a base surface of the cooling fin and the fin so that the cooling efficiency of the cooling fin can be improved. By providing the limiting member, air or atmosphere flowing into the cooling fin is directed to flow toward the fin near the base surface. Further, by providing the limiting member, an area of a portion from which the air or atmosphere flows into the cooling fin is also limited so that the velocity of the air or atmosphere flow becomes high. By these functions and the like, the cooling efficiency of the cooling fin can be increased as compared to the prior art.