A cuff includes: a belt-like body which is adapted to be wrapped around a desired region of a living body a fixing portion which is provided in the body, and which is configured to fix the body in a state where the body is adapted to be wrapped around the region of the living body a pressurizing portion which is provided in the body, and to which a fluid pressure is to be supplied to be inflated to pressurize the region of the living body and an ultrasonic transmissive portion which is provided in the body, and through which an ultrasonic wave for observing a tissue in the region of the living body is transmissible.
