In this paper, we propose a new channel selection method for IEEE 802.11 based wireless local area network (WLAN) using the 2.4GHz band. The proposed algorithm searches the nearby access points (APs) through channel scanning. The scanned APs are classified into shared APs using the target channel and interference APs using the channels adjacent to the target channel. The proposed method evaluates the achievable rate by separately considering the losses by shared APs and interference APs, and selects the channel with the maximum achievable rate. The performance of the proposed algorithm is compared to those of existing channel selection techniques through field tests in practical WLAN environments.