A fluid pump, wherein a cylinder supporting a plunger and a pump housing are formed with dissimilar metals and a pressing mechanism to press the cylinder and the pump housing relatively to each other is provided so that a pressurizing chamber is sealed through a pressing surface between the pump housing and the cylinder, whereby the number of seal points can be reduced 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 using a soft member such as aluminum alloy for the pump housing. <IMAGE>