A method and apparatus of accessing a channel including receiving, by a device, an operation element for setting up or switching at least one channel from an access point (AP), the operation element including a channel type field indicating whether the at least one channel is either a single channel or multiple channels, and including two channel center frequency segment fields indicating a channel center frequency of a primary and a secondary channel if the channel type field indicates that the channel is multiple channels, determining whether the primary channel is idle during a first interval, determining whether the secondary channel is idle during a second interval if the primary channel is idle, and transmitting data by using the primary and secondary channels to the AP or at least one station in a basic service set (BSS) if the primary and secondary channel are idle.