A base station communicates with plural mobile stations using a common channel common to the mobile stations, and a predetermined number of a plurality of shared channels assigned to the mobile stations. The base station includes a scheduler that acquires, for each of the mobile stations, a transmitting power ratio being a ratio of a mobile station assigning power, which is a sum of transmitting powers of the shared channels assigned to the mobile station, and a transmitting power of the common channel. The scheduler determines the mobile station assigning power of the mobile station and then selects communication destination mobile stations, so that a sum of the mobile station assigning powers does not exceed a predetermined maximum assignable power.