An accelerator sensor includes a semiconductor substrate having a main front surface and a main rear surface, a first groove portion being formed along a front surface pattern, in the main front surface, a second groove portion being formed along a rear surface pattern, in the main rear surface, a through-hole being formed because of connection between at least parts of the first groove portion and the second groove portion and at least one groove width variation portion being formed in at least one of inner walls of the first groove portion. An offset of the rear surface pattern to the front surface pattern can be inspected easily by existence of the groove width variation portion.