To provide a water pump capable of providing a delivery opening in a desired direction and keeping operation noise low.

An upper housing 12 is mounted on a main body side housing 14 via a plurality of bolts 2 arranged along a circumference. A desired position is selected from a plurality of mounting positions provided by rotating the upper housing 12 along the circumference phasedly. Consequently, the delivery opening 12b is directed to the desired direction, and both ends of the impeller rotary shaft 18 are supported by a first bearing part 12a and a second bearing part 14a to reduce vibration noise.