In a piston type compressor, a piston is respectively accommodated in a plurality of cylinder bores arranged around a rotary shaft. A rotary valve has a suction guiding passage for introducing gas from a suction pressure region into a compression chamber when in communication therebetween. A suction timing control passage is formed in the rotary valve and is constantly in communication at its first end with the suction pressure region, while preceding the suction guiding passage communicating at its second end with the compression chamber. A suction timing control valve is arranged in the control passage, having a valve body which opens and closes the control passage in response to difference between force resulting from pressure on a side of the suction pressure region to open the valve body and force resulting from pressure on a side of the compression chamber to close the valve body.