A base station for a wireless LAN system has physical layers corresponding to channels, and a MAC layer. The physical layers each transmits and receives a radio signal conforming to an IEEE 802.11 standard using a corresponding channel. When transmitting, the MAC layer divides an entire data frame conforming to the standard from a head of the data frame, in accordance with a transmission rate of each physical layer, and allots the divided data frame to the physical layers so that burst times of the channels are substantially equal. When receiving, the MAC layer combines data frames received via channels through operations opposite to those performed when transmitting.