Disclosed is a dumping work determination system (100) for a haulage vehicle provided with a body frame (2), a vessel (6) and a drive mechanism (14) for selective raising or lowering of the vessel (6). The system is applicable to the vehicle to determine a state of loading in the vessel (6) in dumping work, and includes a body frame speed detector (16), a tilted state detector (17), a shake detector (18), and a payload-stuck state determination unit (191). Based on signals from the detectors, the unit determines whether or not the state of loading is a payload-stuck state. Specifically, the unit determines the payload-stuck state when the speed of the body frame (2) is detected to have reached lower than a predetermined speed, the vessel (6) is detected to have tilted to a predetermined position, and a state where the vessel (6) can be considered to have no longer produced shakes is detected by the shake detector (18).
