A method and an apparatus for increasing transmission coverage of an STA performing an initial access in a wireless LAN are disclosed. An initial access method in a wireless LAN can comprise the steps of: transmitting a trigger frame on a channel by an AP; receiving, by the AP, a first probe request frame transmitted on a first sub-channel by a first STA as a response to the trigger frame; and transmitting, by the AP, on the channel, an MU PPDU including a first probe response frame, which is a response to the first probe request frame, and a second probe response frame, which is a response to the second probe request frame, wherein the channel can include the first sub-channel and the second sub-channel.