A compressor includes a piston (26) reciprocating in a cylinder bore (25). The piston (26) draws refrigerant into and discharges refrigerant from a compression chamber (36) , which is formed between the piston (26) and a valve plate (14). The valve plate (14) has a discharge port (32) connecting the compression chamber (36) to the discharge chamber (17). A guide passage (41) facilitates the flow of the refrigerant from the compression chamber (36) to the discharge port (32). The guide passage (41) is defined in the compression chamber (36) when the piston (26) is located at the top dead center position. This decreases pressure losses that would otherwise occur when the piston (26) is near the top dead center position.