A pump device, comprising: an operating fluid storing portion; a first pump; a second pump having a rotating shaft coaxial with a rotating shaft of the first pump and being provided below a suction opening of the first pump, the second pump being arranged to pump up operating fluid from the operating fluid storing portion; at least one cyclone separator provided in a region above the second pump and below the suction opening of the first pump, for receiving operating fluid pumped up by the second pump and having a function of separating the operating fluid into a clean operating fluid not containing foreign matter (F4, F5) and an operating fluid containing the foreign matter, the cyclone separator being arranged to supply the clean operating fluid to the first pump, and having a cyclone separator outlet for the operating fluid containing the foreign matter; and a discharge opening for the operating fluid containing the foreign matter separated by the cyclone separator; characterised in that: the first pump is a non-positive displacement pump and is provided above the operating fluid storing portion; the discharge opening is provided above the operating fluid storing portion; and a discharge pipe is provided which communicates with said discharge opening from a level of the cyclone separator outlet, wherein in use the operating fluid containing the foreign matter flows through the discharge pipe and is discharged from the discharge opening. an operating fluid storing portion; a first pump; a second pump having a rotating shaft coaxial with a rotating shaft of the first pump and being provided below a suction opening of the first pump, the second pump being arranged to pump up operating fluid from the operating fluid storing portion; at least one cyclone separator provided in a region above the second pump and below the suction opening of the first pump, for receiving operating fluid pumped up by the second pump and having a function of separating the operating fluid into a clean operating fluid not containing foreign matter (F4, F5) and an operating fluid containing the foreign matter, the cyclone separator being arranged to supply the clean operating fluid to the first pump, and having a cyclone separator outlet for the operating fluid containing the foreign matter; and a discharge opening for the operating fluid containing the foreign matter separated by the cyclone separator; characterised in that: the first pump is a non-positive displacement pump and is provided above the operating fluid storing portion; the discharge opening is provided above the operating fluid storing portion; and a discharge pipe is provided which communicates with said discharge opening from a level of the cyclone separator outlet, wherein in use the operating fluid containing the foreign matter flows through the discharge pipe and is discharged from the discharge opening. the first pump is a non-positive displacement pump and is provided above the operating fluid storing portion; the discharge opening is provided above the operating fluid storing portion; and a discharge pipe is provided which communicates with said discharge opening from a level of the cyclone separator outlet, wherein in use the operating fluid containing the foreign matter flows through the discharge pipe and is discharged from the discharge opening.