The present invention provides an apparatus for processing a rubber. The apparatus is equipped with an enclosed kneading chamber; a charging port for charging a material into the kneading chamber; a stirring rotor for stirring the material in the kneading chamber; a control section for automatically controlling the rotational speed of the stirring rotor; and a temperature sensor for detecting an interior temperature of the kneading chamber and outputting the detected information regarding the interior temperature to the control section. The control section automatically controls the rotational speed by a PID control configured to attempt to match the actual temperature with the target temperature until expiration of a control time being set in a state where the material containing a rubber component exists in the kneading chamber, based on the information regarding the actual temperature and information regarding a target temperature being set.