Provided is a channel resource assignment method for fair channel resource reservation in a mesh WPAN, in which the amount of channel resources is fairly reserved when devices share the channel resources. The channel resource assignment method in a mesh Wireless Personal Area Network (WPAN) includes the steps of: (a) transmitting beacons of all devices and adding an amount of channel resource to be reserved to the beacons so as to assign the channel resource for fair channel resource reservation between corresponding devices and adjacent devices when a mesh network is configured; (b) accumulating the amount of the channel resources reserved by all the adjacent devices except the corresponding device; and (c) determining the amount of the channel resources to be reserved.