The invention discloses a device for assisting chest muscle exercise, which comprises a frame body, a massage head, an arm rod, a rubber block, a cushion, an installation room, a rope, a fixed rod, a pulley, a rotating bearing, a slideway, a roller, a connecting rod, and a shaft rod , sleeve, seat plate, support rod and rubber apron. The device for assisting chest muscle exercise of the present invention is compact in structure, convenient in operation, strong in functionality, and novel in design. The structure can effectively massage the back of the human body, saving time and cost. Massage is performed while exercising, thereby effectively and quickly relieving back pain; by adjusting the number of massage structures, the user can effectively adjust the strength of the chest expansion exercise. Adjustment, so as to effectively avoid the situation that the user cannot pull or is too light to achieve the exercise effect.