An abdominal twist exercise device includes a device frame, front and rear rotational axles, a main handle bar, a rotation converter, an adjustable gear, a disengaging lever, a weight, a weight bar, a support rail, a safety handle bar, rotation counters, and a user platform, such that when the main handle bar rotates to one side, the user platform rotates to an opposing side. A rotation converter can include a front chain sprocket, an intermediate rotational axle, an intermediate chain sprocket, a roller chain, an intermediate gear, a rear gear; or a front belt sprocket, a rear belt sprocket, and a twisted belt, connecting the sprockets. Optionally, the front and rear axles can be telescoping.