A variable displacement compressor comprising a cylinder block having a plurality of cylinder bores. The cylinder block has an extension which extends from an outer periphery of an end surface of the cylinder block which faces a swash plate. The extension has an extension surface which forms a part of a bore surface of each cylinder bore and first and second wall surfaces which extend continuously from opposite ends of the extension surface in a circumferential direction of the extension surface. A part of each extension surface which is connected to the first wall surface which is located on a preceding side of rotation of the swash plate corresponds to a high-load area which is locally subjected to loads from a single-headed piston during a compression stroke. The high-load area has a chamfered region which is formed into a curved surface by chamfering.