The present invention relates to a method and a device for updating system information in a wireless LAN system. A method for updating system information in a station (STA) of a wireless communication system may comprise transmitting, by the STA which stores system information and a configuration change count value of a previously linked preferred access point (AP), a probe request frame for active scanning to the preferred AP; and receiving a probe response frame from the preferred AP. Preferably, the probe request frame includes a configuration change count field previously acquired from the preferred AP, and if a value of the configuration change count field included in the probe request frame is different from a present configuration change count value of the preferred AP, the probe response frame may include one or more elements of system information which should be updated by the STA.