First, the strength A of a first pilot signal currently transmitted by a base station and strength B of a second pilot signal transmitted by a base station other than the foregoing base station are measured, the correction value D of a handoff threshold value according to the multicast service availability and radio configuration information of the multicast content is obtained, and handoff threshold value C is obtained, as well. Next, if the difference between the strength B of the second pilot signal and the strength A of the first pilot signal is greater than the sum of the handoff threshold value C and the correction value D, the idle handoff is started. Through this, idle handoff to neighbor base stations delivering the same multicast content is facilitated and idle handoff to other base stations is made difficult.