The invention relates to a method for a station (STA) to perform channel access in a wireless communication system, comprising the steps of: receiving a beacon frame including a traffic indication map (TIM); a step of checking, if the TIM indicates to the STA that buffered traffic exists, information relating to a PS-poll transmission type; and a step of transmitting a PS-poll frame according to either a first type or second type of transmission indicated by the information relating to the PS-poll frame transmission type. The first type of transmission involves transmitting the PS-poll frame after performing contention, and the second type of transmission involves transmitting the PS-poll frame in the time interval set for the STA.