A method for updating system information in a terminal in which data is transmitted by means of superframes, includes: receiving system information, scheduling periodicity information of the system information and changing information indicating changing status of the system information transmitted by means of a superframe header (SFH) from a base station; and updating the system information based on the changing information, wherein the SFH comprises a primary SFH including the changing information and a secondary SFH including at least one subpacket containing the system information, the scheduling periodicity information indicating a transmission periodicity of the subpacket is transmitted by means of the primary SFH or a predetermined subpacket, and when the terminal detects that a changed system information transmitted by means of the subpacket is not scheduled as indicated in the scheduling periodicity information, the terminal wakes up until the changed system information is received.