A ranging method in a mobile station of a femto system is disclosed. According to the present invention, a femto base station enables non-synchronized ranging channel (NS-RCH) information to be carried on S-SFH SP1. A mobile station receives S-SFH and then determines whether a base station is a femto base station. If the base station is the femto base station, the mobile station is able to perform a periodic ranging using the NS-RCH information within the S-SFH as well as an initial/handover ranging.