Disclosed are a channel access method and device in a wireless LAN system. The channel access control method comprises the steps of: receiving, from a main-access point, a main-beacon frame including information on an limited access section in which a channel access of an end terminal connected to a relay device is limited; generating a relay-beacon frame including the information on the limited access section; and transmitting the relay-beacon frame. Thus, the efficiency of using a wireless channel can be improved.