A fluid pump has a cylinder supporting a plunger and a pump housing formed with dissimilar metals. A pressing mechanism presses the cylinder and the pump housing relative to each other so that a pressurizing chamber is sealed through a pressing surface between the pump housing and the cylinder. The number of seal points can be reduce, and a reduction in reliability can be eliminated while realizing a reduction in weight of the pump housing and a reduction in cost due to increase in cutting capability, by using a soft material such as an aluminum alloy for the pump housing.