Various techniques have been proposed concerning a conventional power semiconductor module including a case within which a sealing resin (gel) is filled. One example of such techniques is using an adhesive (sealant) order to prevent moisture from entering the inside of the ease via a joint and a fixing portion between the case and a base plate (heat-dissipation plate) (e.g., Patent Document 1). Another example is, without using the adhesive, forming a protrusion and a recess in the case and the base plate (heat-dissipation plate), and then fitting them to fix the case and the base plate (e.g., Patent Document 2).