To provide an ultrasonic transmitter-receiver that can significantly avoid the occurrence of adverse crosstalk.

This ultrasonic transmitter-receiver is provided with an ultrasonic converter 1, an ultrasonic waveguide 2, and an external peripheral wall 3. The waveguide 2 is arranged inside the peripheral wall 3, and the converter 1 is arranged at one end section 4 of the waveguide 2. In addition, the converter 1 at the end section 4 of the waveguide 2 can transmit or receive ultrasonic waves to or from the waveguide 2. In the transmitter-receiver, in addition, an impedance discontinuing section is provided between the converter 1 and an area of the peripheral wall 3 on the side separated from the converter 1.