A channel access method for a very high throughput (VHT) system using a bonding channel having a plurality of subchannels is provided. The method includes receiving training information comprising a training offset value through a subchannel, performing channel estimation on a full channel bandwidth comprising all subchannels when a time corresponding to the training offset value is elapsed after the training information is received, transmitting a request to send (RTS) frame to a destination station through some subchannels selected from the plurality of subchannels by one or a plurality of source stations according to a result of the channel estimation, and transmitting a clear to send (CTS) frame to one source station selected from the plurality of source stations by the destination station in response to the received RTS frame. Accordingly, an effective channel access mechanism is provided for the VHT system, and collision among stations can be avoided.