A double-headed piston compressor includes a pair of opposite discharge chambers. Each discharge chamber is defined by a large annular wall and a small annular wall. The annular walls are located about the axis of the drive shaft. A limit wall is formed in each housing and is located in each discharge chamber. Each limit wall extends substantially radially to connect the annular walls near the outlet of the discharge chamber. Therefore, each discharge chamber forms a gas passage, which extends circularly about the axis of the drive shaft from the limit wall to the outlet. Compressed gas discharged from the cylinder bores to each discharge chamber through the discharge ports flows in one direction toward the outlet. As a result, pulsation of compressed gas is attenuated.