Disclosed herein are embodiments of a pressurized-oil supply amount control device for a vehicle-mounted crane which has a dual pump system and which is capable of further inhibiting possible noise from an engine and improving fuel consumption. A predetermined control function is set for a controller 2 for the pressurized-oil supply amount control device. Three regions R1, R2, R3 are set for the predetermined control function according to the rate of an operation signal input. Based on the predetermined control function, the rotation speed of the engine 6 is controlled, and the flow rate of pressurized oil is controlled by a flow rate control valve 5. This increases the total flow rate G of pressurized oil supplied to a control valve 3 in proportion to the rate of the operation signal input to the crane.