A semiconductor device includes: terminals that include a terminal obverse surface and a terminal reverse surface; a semiconductor chip that is mounted on the terminals; and an encapsulating resin for encapsulating the terminals and the semiconductor chip. The terminals include: a terminal portion that includes a terminal portion reverse surface, which is exposed from the encapsulating resin on the terminal reverse surface; a mounting portion that extends from the terminal portion in a first direction orthogonal to a Z direction, which is the thickness direction of the terminal, and has the semiconductor chip mounted thereon; a groove portion that is provided at least in the mounting portion and extends in the first direction; and wall portions that are positioned at both ends in a second direction orthogonal to both the Z direction and the first direction by the groove portion and extend in the first direction.