There are provided an apparatus and method for transmitting power headroom information in a multiple component carrier system. The method includes finding Combination Power Headroom (CPH), that is a power headroom, calculated in an User Equipment (UE)-specific way with consideration taken of uplink transmission through a plurality of component carriers configured in the UE, generating CPH information used to inform an evolved NodeB (eNodeB:eNB) of the CPH, and sending the CPH information to the eNB. According to the present invention, power headroom for a combination component carrier is provided to an eNB in a wireless communication system in which a carrier aggregation is used. Accordingly, reliable dynamic carrier aggregation scheduling can be induced, and thus uplink transmission performance can be improved.