An oil pump structure including: an oil pump having a first hydraulic control chamber and a second hydraulic control chamber; a hydraulic control valve having a valve operating oil passage, a first inflow passage, a second inflow passage, a first outflow passage, a second outflow passage and a drain flow passage; and an oil circuit, wherein the hydraulic control valve is connected to a branching flow passage of the oil circuit; a spool valve body of the hydraulic control valve has a front valve section, a rear valve section and an intermediate valve section, which are formed perpendicularly to the axial direction of a connecting shaft; an axial-direction dimension of the intermediate valve section is larger than an axial-direction dimension of the second outflow passage; the second outflow passage and the drain flow passage are both accommodated temporarily between the intermediate valve section and the front valve section due to movement of the spool valve body; and in the hydraulic control valve, a control hydraulic pressure is applied at all times to the first hydraulic control chamber, and the control hydraulic pressure is increased and decreased in the second hydraulic control chamber.