100 may operate for example as follows at step s 101 in fig3 the control section 170 monitors the frequency error signal d_error which is from the frequency comparator 110 at that time the control section 170 may use a temporal average of the frequency error signal d_error for monitoring the frequency error signal d_error by so doing the control section 170 can reduce the influence of a noise component included in the frequency error signal d_error when monitoring the frequency error signal d_error further at step s 103 in fig3 similarly the control section 170 may use a temporal average of the control voltage signal d_vtune for obtaining the control voltage signal d_vtune by so doing the control section 170 can reduce the influence of the noise component included in the control voltage signal d_vtune when obtaining the control voltage signal d_vtune by using the temporal average of at least either one of the frequency error signal d_error or the control voltage signal d_vtune as described above the control section 170 can set a value that reduces the influence of the noise component at step s 104 further in the example described above the control section 170 calculates the temporal averages of the frequency error signal.