An apparatus for controlling a variable displacement compressor has an information detector and a controller. The information detector detects information about the thermal load on the refrigeration circuit. The controller determines a target value that reflects the displacement of the compressor based on the information about the thermal load detected by the information detector, and outputs the target value as a command value. When determining that the compressor is in a heavy load state based on information about a load on the compressor, the controller changes the command value to a value that causes the displacement of the compressor to become smaller than a displacement that corresponds to the determined target value.