The present invention relates to a robot apparatus and an output control method adapted for the robot apparatus. The method includes steps of: receiving radio frequency (RF) signals of identification (ID) codes from several wireless communication devices within a predetermined area and time period; sensing people and obtaining the number of people within the predetermined area and time period; comparing current ID codes and the number of people in the predetermined area with what were determined previously, generating an update signal when the comparison is not equal; replacing the previous data with the current data; acquiring output data based on the associated output found in the output table; and performing an output based on the output data.