Signals outputted from microphones 111 and 112 are inputted through filters 118 and 119 to noise suppressing sections A and B. One having smaller power is selected from output signals S107a and S107b by switching a selection switch SW in a signal power comparing section 117, to which the output signals S107a and S107b have been inputted, and a transmission signal S108 level-adjusted by a level adjuster is outputted. In the noise suppressing section A (similarly in the section B), microphone output signals S102 and S103 are processed by an adder 113a and a subtracter 114a, a signal S105a outputted from the subtracter 114a is inputted to a subtracter 116a through a filter 115a having a transmission function Fa(z) decided by the positions of the microphones 111 and 112 and a noise suppression signal S107a obtained by subtracting the signal S105a from a signal S104a outputted from the adder 113a is outputted.