PURPOSE: To decrease a measuring error and also to attain small size and light by holding an ultrasonic wave vibrating part performing thickness vibration and an ultrasonic wave vibrating part performing radially spread vibration onto a single case so that center axes are made coincident with each other.

CONSTITUTION: A truncated cone packing member 3 is formed on one side of the thickness vibrating disc type vibrator 1 made of a piezoelectric ceramic. Further, the radially spread vibrating cylindrical vibrator 2 having a center axis coincident with the center axis 6 of the vibrator 1 and the packing member 3 are formed and a hollow cylindrical packing member 4 is provided between an outer circumferential sine face and a case 5. In making the top spread angle θ of the packing member as 45°, an ultrasonic wave by the vibrator 2 is irradiated forward. Since the ultrasonic wave of a high frequency is transmitted by the vibrator 1 and the ultrasonic wave of a low frequency is transmittd by the vibrator 2, the measurement from a short range to a long range is conducted with high accuracy.