The invention discloses an abdominal 
muscle exercising apparatus. The abdominal 
muscle exercising apparatus comprises a supporting 
pipe made of aluminum 
alloy, a speed change mechanism and idler wheels which are arranged in pair, and the idler wheels which are arranged in pair are installed on the supporting 
pipe; the speed change mechanism in installed at the inner side of one 
idler wheel. When abeginner uses a power roller, the speed change mechanism generates resistance in a forward pushing process, and the direction of holding the power roller can be adjusted; when the power of the handsor the 
abdomen reaches the limit and cannot provide enough support, a reversing button can be pressed, a motor in the supporting 
pipe rotates, a driven rotor rotates, a 
magnet b on the driven rotor drives a 
magnet a on an annular gear to rotate, the annular gear rotates, a gear b is driven, a gear a drives a gear d, a gear c drives an inner gear on a drive base to rotate, the drive base makes theidler wheels reduce speed, backward force is generated to make the idler wheels reciprocate, thus the rotation of the idler wheels is conveniently controlled, and the situation that a user suffers from 
muscle strains when the idler wheels are out of control during rolling is prevented.