A muscle electrostimulation device (10) has a main body (20) having a contact surface (10b) fitted around an abdomen (3). The contact surface (10b) extends in an X direction encircling the abdomen (3) and in a Y direction perpendicular to the X direction. The main body (20) includes: a front part (22) having a front electrode unit (32) adapted to cause an electric current in the X direction in an abdominal rectus muscle (4)； and a pair of extensions (26) extending from respective sides of the front part (22) in the X direction and having side electrode units (36) adapted to cause an electric current in the X direction to flow in an oblique abdominal muscle (5). Front recesses (23) that recede in the Y direction are provided at positions in side portions (22b) of the front part (22) along the Y direction that bisect the front part (22) in the X direction.
