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.一種肌肉電性刺激裝置，係能夠減少往身體裝戴的時間且能夠同時訓練腹直肌與腹斜肌。在肌肉電性刺激裝置中具備：本體部20，係具有沿著腹部之周圍所裝戴的裝戴面10b。裝戴面10b係朝向圍繞腹部的X方向以及與X方向正交的Y方向延伸。本體部20係包含：正面部22，係具有用以使X方向之電流流動至腹直肌的正面電極部32；以及一對伸出部26，係從正面部22朝向X方向之兩側伸出，且具有用以使X方向之電流流動至腹斜肌的側面電極部36。在正面部22之Y方向的側部中之將正面部22於X方向對分的位置設置有朝向Y方向凹陷的正面凹部23。
