A vehicle air-conditioner compressor may include a housing having a front housing section and a rear housing section; a shaft rotatably installed in the housing; a lug fixed at a preset position on the shaft; a swash plate coupled with the lug at one side thereof and rotating together with the lug, a piston connected to the swash plate by a shoe and moved reciprocatingly by the swash plate; a cylinder that accommodates the piston therein, and a pressure-sensing chamber coupled with a rod at the other side of the swash plate, that operates the rod using a pressure provided from a high-pressure chamber of the rear housing.