A relief valve structure (20) attached to a pump body (10) includes: a first discharge portion (31) for discharging oil when a discharge pressure is a first predetermined pressure; a second discharge portion (32) for discharging the oil when the discharge pressure reaches a second predetermined pressure higher than the first predetermined pressure; a third discharge portion (33) for discharging the oil when the discharge pressure exceeds the first predetermined pressure and reaches the second predetermined pressure or a pressure lower than the second predetermined pressure; and a pressure relief hole (34) for releasing the oil from an area around a valve spring (23). The second discharge portion, the first discharge portion, the third discharge portion, and the pressure release hole are provided in this order between an introduction portion (29) and a spring retaining member (24) when viewed from the introduction portion (29).