Practice Guidelines for the Treatment of Tuberculosis

An ultrasonic sensor includes a case member and a piezoelectric element. The case member has a hollow therein and a bottom portion provided at one end of the hollow. The bottom portion has a thick portion which extends along a first direction and a pair of thin portions which have a smaller thickness than the thick portion and are provided on opposite sides of the bottom portion along a second direction. The piezoelectric element radiates and/or detects ultrasonic energy and is provided at a center of the thick portion on an inner surface of the bottom portion.