A pump includes a cylinder and a plunger. The cylinder defines an outlet-side passage therein. The plunger is reciprocably received within the cylinder. An inner peripheral surface of the cylinder and an end surface of the plunger define a pump chamber. The outlet-side passage is communicated with the pump chamber. When the plunger reciprocates within the cylinder, fluid inside the pump chamber is pressurized such that fluid is discharged to an exterior through the outlet-side passage. The inner peripheral surface includes a spherical surface part that surrounds the pump chamber. The spherical surface part is defined by a curved surface having a predetermined curvature such that the pump chamber defines a spherical space. The spherical surface part is provided with an opening of the outlet-side passage, which has a circular shape when observed from a spherical center of the pump chamber.