PURPOSE: To measure simply the height with no contact, by transmitting the ultrasonic wave to the head part of a human body, cutting the signals of the reflected wave lower than a certain level and measuring the time during which the reflected wave arrives.

CONSTITUTION: The ultrasonic pulse is transmitted from an ultrasonic converter 2 via a driving signal generating circuit 1, and the wave reflected from the top of a man M to be measured is detected by the converter 2. Then an FF18 is set by the output signals higher than a prescribed level via an amplifying circuit 15 and a wave detecting circuit 16. The output of an FF 17 which is kept at an output H by a trigger circuit 11 and just for the time during which the ultrasonic wave propagates back and forth between the converter 2 and a floor surface 14 and the output of the FF18 apply the signal which is set at H just for the time during which the ultrasonic wave propagates back and forth a distance corresponding to the height of the M to a counter 20 via a gate circuit 10. The output pulses of a clock oscillator 7 are counted, and the count value corresponding to the height is displayed 5. In such way, the height can be simply measured without contacting.