A power semiconductor device includes a power semiconductor module having cylindrical conductors which are joined to a wiring pattern so as to be substantially perpendicular to the wiring pattern and whose openings are exposed at a surface of transfer molding resin, and an insert case having a ceiling portion and peripheral walls, the ceiling portion being provided with external terminals that are fitted into, and passed through, the ceiling portion, the external terminals having outer-surface-side connecting portions at the outer surface side of the ceiling portion and inner-surface-side connecting portions at the inner surface side of the ceiling portion. The power semiconductor module is set within the insert case such that the inner-surface-side connecting portions of the external terminals are inserted into the cylindrical conductors.