A saddle-adjusting mechanism of a fitness apparatus having: a) a set of upper and lower parallel slide rails pivotally attached to a front and a rear connecting rod; and b) a saddle support with guide rollers and an engaging gear such that the upper and lower parallel slide rails may be adjusted at a certain angle. Meanwhile, a saddle can be moved forward and backward and maintained at a certain angle so that the operators have a comfortable sitting. Moreover, a back pad support is installed in such a way that a fine adjustment of the backing angle of a back pad is achieved by moving it upward and downward.