A rotation control system of a hoist pump includes: the hoist pump (3); an engine (2) for driving the hoist pump (3); a working equipment driven by a hydraulic cylinder that is extendable by hydraulic oil delivered through the hoist pump (3); a hydraulic oil tank that stores the hydraulic oil supplied to the hoist pump (3) and receives the hydraulic oil returned from the hydraulic cylinder; and a controller (9) that controls a rotation speed of the hoist pump (3) to be an allowable rotation speed that is set in advance for preventing cavitation while the hydraulic cylinder is operated.