The invention provides a structure of a horse riding machine and directs to a mechanism composed of a swinging device and a guiding device. The mechanism can produce the back-and-forth motion, the swinging motion, and the left-and-right and up-and-down motions and thus the 8-shaped motion. Thus, the effect of actually riding a horse can be obtained such that the horse riding machine having the effect of overall exercising the buttock, the waist and the leg and the body-shaping effect can be obtained.