To provide a device and method of measuring propagation time capable of simply and correctly measuring the propagation time without needing skill or burden of an operator.

The ultrasonic wave propagation time measuring device comprises: an ultrasonic sound probe; and a pressing means including the pressing member for pressing the measured object together with the ultrasonic probe as a pair for holding and pressing the measured object on the ultrasonic probe. The method of measuring the propagation time is that by using the ultrasound probe and the pressing means for pressing the measured object, by sandwiching the contact medium between the ultrasound probe and the measured object, the measured object is pressed while being sandwiched in-between by the ultrasonic wave probe and pressing means, and the measurement is performed after certain time has elapsed after pressing the measured object as above described.