Abstract: A sliding-vane rotary compressor includes a first control valve responsive to the pressure in a low pressure chamber for adjusting the rate of communication between a high pressure side and a low pressure side, and a second control valve operative in the same manner as the first control valve under the control of an external signal. With this construction, an optimum displacement control of the compressor is achieved. Also disclosed is an apparatus for controlling a variable displacement compressor, in which a solenoid valve is controlled depending on internal and external thermal load conditions of the compressor for selectively blocking fluid communication between high and low pressure sides.