Abstract: A semiconductor device capable of preventing moisture from entering into a package and also capable of preventing peeling between a pad and the package from occurring. The semiconductor device comprises grooves formed on a semiconductor element mounting surface of the pad to surround the semiconductor element, plated portions formed on only a ground bond area of the semiconductor element mounting surface of the pad, a thin portion formed on an entire peripheral edge portions on the back of the pad, and thin portions formed at portions which connect with the pad, on backs of support bars extending from the pad.