The invention discloses a riding type rice transplanter. The riding type rice transplanter comprises an engine, a power source, a front axle, front wheels, a rear axle, rear wheels, a chassis frame, a whole transplanter frame, a rice transplanting part, a steering system and a speed change gear used for driving the front wheels and the rear wheels to rotate. The chassis frame is fixedly installed on the front axle and the rear axle. The whole transplanter frame is located above the chassis frame, fixedly connected with the chassis frame and connected with the front axle and the rear axle, the whole transplanter frame extends out of the front axle along the front end of the rice transplanter, and the rice transplanting part is arranged on the extending-out part. An engine seat for installing the engine is installed on the chassis frame and located in the middle of the riding type rice transplanter, and the engine is fixedly installed on the engine seat. The engine is arranged in the middle part and thus is protected against damage. An integrated frame mechanism is formed, the stability of the whole transplanter body structure is achieved, and the tensile strength and the torsion property of the whole transplanter are improved.