The present invention relates to a power control apparatus and method for preventing a system from being repeatedly booted and shut off by re-setting a cut-off voltage when the system is shut down by a cutoff mode. The power control apparatus of a terminal device according to the present invention comprises a power controller 30 for controlling power supplied from a battery 10 to the terminal device; and a memory 60 for storing a cutoff voltage value for shutting down a system if a voltage of the battery 10 is lower than a reference value, wherein the power controller 30 sets a flag when the system is shut down by a cutoff mode. When the system is rebooted, it is determined whether to drive the system based on an additional cutoff voltage, if the flag is set. According to the present invention, it is possible to prevent the system from being shut down by the cutoff mode after it has been driven. Therefore, there is an advantage in that the life span of the battery can be extended and the charging time of the battery can be saved.