A semiconductor device according to the present disclosure includes: a plate (13) having a through hole (15); a metal column (16) fixed to the through hole with an insulating member (17) interposed therebetween, and having a projection projecting from the upper surface of the plate; a semiconductor element (12) fixed to the projection; a lead frame (11) electrically connected to the semiconductor element; and a package (14) covering the semiconductor element, and also covering at least part of each of the plate, the metal column, and the lead frame. The lower surface (13b) of the plate is exposed from the package.