The present invention relates to a wireless communication system, and more particularly, to a method and apparatus for updating system information in a wireless LAN system. A method for a station (STA) to update system information in a wireless communication system according to one embodiment of the present invention comprises the steps of: if the value of a change sequence field received by the STA from an access point (AP) is different from the value of the change sequence field stored in the STA, transmitting, to the AP, a probe request frame including the change sequence field set to the value of the change sequence field stored in the STA; and a step of receiving, from the AP, a probe response frame responding to the probe request frame including the change sequence field.