A reciprocatory piston type compressor is provided with partition walls in a discharge chamber or chambers, the walls being arranged between discharge ports open to the discharge chamber, respectively, to prevent flows of refrigerant gas discharged from the discharge ports from directly interfering with each other at least during the time in which the opening of two adjacent discharge reed valves overlap one another. The partition walls may be formed integrally with a cylinder head of the compressor in such a manner that the partition walls extend centripetally from an inner wall surface of the cylinder head defining the discharge chamber. The flows of refrigerant gas discharged from the two adjacent discharge ports which are open will not interfere with each other but will be guided independently and centripetally along the partition walls in the discharge chamber toward the tops of the partition walls, and then toward an opening that leads to an outer discharge conduit.