An inner cutter unit, which is used in an electric rotary shaver, including an inner cutter base, which is connected to the axle of the motor of the shaver and rotated, and an inner cutter body, which is disposed on the inner cutter base. The cutting head has a plurality of cutting teeth. Enclosed within the space is an absorbent cord. The MEMS device structure includes a fixed mass and a proof mass. Of respective edge portions 1X, 1Y of the two cloth members 4, 4\u2032 forming the opening 101, an upper end of one of the edge portions is joined in an overlapped manner to the other cloth member; and lower ends 1B, 1D of the two edge portions 1X, 1Y are jointed to each other at a width-wise center 16 of the front opening portion 100.