A compressor includes a cylinder block and a housing connected to the ends of the cylinder block. A suction chamber and a discharge chamber are defined in the housing, respectively, and the chambers are divided by a bulkhead, or wall. A valve plate, which has a discharge port for connecting the cylinder bores with the discharge chamber, is positioned between the cylinder block and the housing. A discharge valve is provided for selectively opening and closing the discharge port. A gasket is positioned between the housing and the valve plate, and the gasket is held to the bulkhead. The gasket has a bulkhead seal portion, which is between the bulkhead and the valve plate for sealing between the discharge chamber and the suction chamber, and a protruding portion, which protrudes radially beyond the bulkhead, extending along and contacting the valve plate.