A hydraulic power generator is provided to optimize the length and cross-sectional area to a receiving space of an inside-vehicle hydraulic power generator. A hydraulic power generator comprises a housing(10) and a rotation shaft(40). The housing comprises a pump housing(20) and a motor housing(11). The pump housing has a second hollow part(21) in which a pump unit(50) is arranged. The motor housing has a first hollow part(15) in which a stator(31) and a rotor(32) are arranged in inside. The motor housing comprises a joint(16) and an enlargement part(12). The joint is combined in one side of the pump housing. The enlargement part is extended from the joint and the first hollow part is formed in the inner side. The cross-sectional area of the enlargement part of formed the get larger the farther to the first hollow part. The rotation shaft is pivotally supported in the housing and the torque of the rotor is delivered to the pump unit by being rotated with the rotor.
