The supply and the discharge of pressurized oil with respect to a hoist cylinder (12) that tilts a vessel (3) is controlled by a control valve device (19). A throttle (24C), which restricts the flow volume of operating oil discharged from a hydraulic pump (13) and flowing to a return pipeline (16) via a pump pipeline (15), the first direction control valve (24), and a center bypass oil passage (23), is provided at the floating position (F) of a first direction control valve forming the control valve device (19). When the first direction control valve (24) is in the floating position (F) the upstream side of the throttle (24C) connects to the pump pipeline (15) and the downstream side of the throttle (24C) connects to return pipeline (16), and a rod-side actuator pipeline (18), which communicates with rod-side oil chambers (12E, 12F) in the hoist cylinder (12), connects to the pump pipeline (15).