A mounting structure for mounting a jet propulsion pump in a body of a personal watercraft includes, a front mounting portion of the pump being mounted to a rear portion, in a planing direction of the watercraft body, and a ride plate mounted to the watercraft body, so as to be located beneath the pump, wherein the ride plate is mounted to watercraft body in at least two positions in the planing direction of the watercraft body. Further, an elastic member is disposed between the ride plate and the pump, such that a rear portion of the pump is supported by the ride plate through the elastic member.