To provide a pump suitable for cooling a personal computer or the like.

The cam-type pump of the invention is constituted as follows. A body 3 has a cylindrical space 3a therein. A rotary shaft is provided at the center of the space 3a of the body 3. A cam cylindrical member 8 having a cam surface formed on one side face thereof is attached to the rotary shaft. A roller 15 is provided to come in close contact with the side face of the cam cylindrical member 8 and to rise/set, following rotation of the cam cylindrical member 8. Due to the protruding/retreating function of the roller 15, fluid sealed in a hollow portion 9 formed between the cam surface 7 of the cam cylindrical member 8 and an inner peripheral wall 3b of the body 3 defining the space 3a is compressed and discharged to the exterior from a discharge port 19. Further, when the cam cylindrical member 8 rotates to the side opposite to the side of the discharge port 19, the pressure of the hollow portion 9 is made negative to thereby promote the filling of fluid from the exterior into the hollow portion 9.