A non-contact ultrasonic tonometer for measuring intraocular pressure of an examinees eye, in non-contact manner by use of an ultrasonic wave comprises: a probe including a vibrator for making the ultrasonic wave incident on the examinees eye and a sensor for detecting the ultrasonic wave reflected from the examinees eye and an observation optical system for observing an anterior segment of the eye, wherein the probe is placed in an optical path of the observation optical system, and the observation optical system forms an image of the anterior segment through a surrounding region of the probe.