A multifunction apparatus according to the present invention transmits an electromagnetic wave signal to a memory card carried by a user who enters a detection area, scans identification information of the user for user authentication, and starts a warm-up operation immediately after the authentication. Accordingly, the time period spent by the user starting from the user's arrival at the multifunction apparatus until the completion of the warm-up operation is shortened. In addition, the multifunction apparatus determines whether the user remains in the detection area after a job is completed, and transitions from a normal mode to an energy-save mode when it is determined that the user is not remaining in the detection area, the normal mode being in a state where sufficient electrical power is supplied for a job execution, the energy-save mode being in a state where the power supply is decreased compared to the normal mode.