A blood pump (100) according to the present invention includes: a base body (110) ； a casing (120) fitted on the base body (110)； a blood supply mechanism housed in a pump chamber surrounded by the base body and the casing； and a drive element supplying energy to the blood supply mechanism. The base body (110) has: an approximately horizontal surface (111) including a first contact surface (113) which is brought into contact with the casing (120)； and a first engaging portion (115) including a first tapered portion (116) which is inclined inward as the first tapered portion (116) extends downward. The casing (120) has: a casing body (121) having a second contact surface (122) at a position which corresponds to the first contact surface (113)； and a second engaging portion (126) formed at an edge side of the casing (120) and including a second tapered portion (126) which is inclined toward an r direction as the second tapered portion (126) extends upward from an inner end portion (127). The second engaging portion engages with the first engaging portion, and the second contact surface of the casing is pressed so as to be brought into contact with the first contact surface of the base body. The formation of a gap between the second contact surface and the first contact surface is prevented. It is also possible to provide a blood pump having a small diameter and a small volume.
