Disclosed is a seat adjustment apparatus for a mobility vehicle, in which a seat cushion slides in a forward/rearward direction while moving upward or downward when the seat cushion is tilted, thereby allowing an occupant to take a stable posture. In one aspect, the seat apparatus comprises 1) a fixing bracket fixed to a floor surface; 2) a setting bracket disposed above the fixing bracket and connected to a back frame so that the back frame is rotatable; 3) a guide unit disposed at a front end of the fixing bracket and a front end of the setting bracket; 4) a guide part disposed at a rear end of the fixing bracket and a rear end of the setting bracket; and 5) a drive unit connected to the guide unit.