PURPOSE: To reduce the phase error at the same band, to widen the band at the same phase error, and to reduce the relative phase characteristics, by providing the phase shift unit having the first and second balance modulator and filter so that the relative phase difference can be reduced with the transmission unit.

CONSTITUTION: The delay unit and the phase shifter 11 in which the phase is linearly varied with the frequency or equivalent are provided and they are constituted so that the relative phase difference can be reduced to the transmission units 2a and 2b and the transmission line 3 and the lime. Further, the phase shifter 11 consists of the terminal 21 to which the input signal is fed, terminal 22 from which the carrier is fed, first and second balanced modulators 23a and 23b providing the function to obtain the sum and difference of the both frequencies of the carrier and the modulation wave, filters 24a and 24b inputting the output, and the phase shifter 25 inputting the carrier from the terminal 22 and feeding the modulators 23a and 23b. Thus, with a simple constitution, the reduction in the phase error can be made with the same band.