To make it possible to appropriately implement frequency adjustment at a direct communication side without performing regular maintenance work.

An internal frequency deviation measuring unit 27 compares the number of clocks at a base station communication side counted by a base station communication side clock counter unit 18 with the number of clocks at a direct communication side counted by a direct communication side clock counter unit 28, and calculates a deviation amount between a base station communication side clock frequency and a direct communication side clock frequency. If the frequency deviation amount is equal to or more than a threshold value, a direct communication side reference frequency setting storage unit 24 calculates a control voltage value corresponding to a reference frequency which will be an initial value of the frequency of the direct communication side clock, and updates reference frequency information on direct communication. This allows the reference frequency information on direct communication to be automatically updated, which achieves a state in which next direct communication is started with optimal frequency setting.