and the filter constant to be used for quality evaluation are set on the basis of the comparison result for example assume that the comparison result indicates that the calculated sir is equal to or larger than the reference value in this case the search controller 13 determines that the communication quality of the active cell is sufficiently high and therefore cell search for the active base station need not be executed frequently in step s 4 the frequency of cell search for the active base station is set to e g u201c 0 1 u201d the handoff controller 6 is notified of the set frequency the value u201c 0 1 u201d indicates that search for the active base station is executed once for every 10 cycles of search for the neighboring base stations in step s 5 the search controller 13 sets the filter constant to 1 1 and gives the set filter constant to the cell quality evaluator 14 the value 1 1 represents that register length 1 and weight coefficient 1 in the cell quality evaluator 14 all the switches in the switch circuit 34 are turned off weight coefficient 1 is output from the register 33 for this reason a value obtained by multiplying the sir obtained in the latest cell search by weight coefficient 1 is sent to the search controller 13 through the adder 35 as a quality evaluation value in step s 8 at least the next cell search for the active base station is executed once for every 10 cycles of cell search for.