To provide a riding type paddy field work machine which can be turned lightly without damaging a paddy field and is excellent in operability at the time of turning a machine body.

An engine 11 is disposed in the front of the machine body, a transmission case 9 having a small lateral width and provided with right and left steered front wheels 1 is disposed in the rear of an engine 11, a hydrostatic continuously variable transmission 41 connected to one lateral side of the transmission case 9 and the engine 11 are connected to interlock, and traveling power speed-changed by the transmission case 9 is transmitted to the right and left front wheels 1 and right and left rear wheels 2 disabled from steering, which are provided in the rear part of the machine body. The right and left rear wheels 2 are respectively provided with a side clutch 96, whereby when the front wheels 1 are steered over a preset reference angle, the side clutch 96 corresponding to the rear wheel 2 taking the inside position in turning is automatically disconnected.