A semiconductor device includes a base plate; a metal plate above the base plate; a bonding material between the base plate and metal plate, bonding the metal plate to the base plate; an insulating plate on the metal plate; a circuit member on the insulating plate; a semiconductor element mounted on the circuit member; and a sealing material to seal a space on the base plate. The metal plate includes a bottom surface area along a periphery, exposed from the bonding material. The base plate includes a groove-shaped first recess formed along the periphery of the metal plate and faces the bottom surface area. The base plate also includes a groove-shaped second recess that is spaced apart from the first recess and that is formed on the inner side relative to the first recess. The bonding material is disposed in at least a part of the second recess.