A method and a device for allocating resource units in a wireless LAN are disclosed. The method for allocating resource units in a wireless LAN can comprise the steps of: scheduling, by an AP, wireless resources for communicating with an STA on a bandwidth; and transmitting, by the AP, downlink data to the STA through the wireless resources, wherein the wireless resources are determined on the basis of a resource allocation combination according to the bandwidth size, and the resource allocation combination is a combination of at least one resource unit allocable on the whole available tone according to the bandwidth size, and the whole available tone can be a multiple of 242 tones according to the bandwidth size.