PURPOSE: To enable the decision of the hair cycle or presence or absence of hair regeneration activity without giving a physical or mental pain to a testee.

CONSTITUTION: Ultrasonic waves are transmitted to the biotissue from a signal transmission section. The ultrasonic waves reflected from the boundary of the biotissue varying in the acoustic impedance are received in a signal reception section 3. The time after the signal is transmitted before the reflected waves are received is converted and calculated to a distance in a time/distance conversion section 8. The distance is computed in an arithmetic section 9, by which at least ≥1 kinds among the diameter of the hair bulbs, the depth of the hair roots and the distance between the hair bulbs and the hair protuberantia are measured. The hair cycle or hair regeneration activity is decided in accordance with the measured values obtd. in such a manner.