A lubricating structure in a fixed displacement piston type compressor has a housing, a rotary shaft, a cam, a piston, a rotary valve and a rotary body. The housing defines a cam chamber, cylinder bores and a suction pressure region. The rotary shaft is rotatably supported by the housing. The cam is located in the cam chamber and is connected to the rotary shaft. The piston is located in each of the cylinder bores and engages the cam to reciprocate with rotation of the rotary shaft through the cam. The rotary valve connected to the rotary shaft includes an introducing passage and a supply passage that interconnects the introducing passage and the suction pressure region. The introducing passage introduces fluid into the cylinder bores through the supply passage. The rotary body connected to the rotary shaft includes a communication passage that interconnects the cam chamber and the suction pressure region.