Ultrasonic sensor

An ultrasonic sensor for detecting an ultrasonic wave, which is output from an ultrasonic generator and reflected by an object to be detected, the ultrasonic sensor comprising:

• an acoustic matching layer having a first surface and a second surface, the first surface which receives the ultrasonic wave, and the second surface which is opposite to the first surface;
• an ultrasonic detection element including a vibration member;
• and
• a transmission member disposed between the vibration member and the acoustic matching layer member, wherein
• the vibration member is coupled with the second surface of the acoustic matching layer,
• the acoustic matching layer is repeatedly deformable in accordance with a standing wave, which is generated in the acoustic matching layer by the received ultrasonic wave,
• the vibration member resonates with the repeat deformation of the acoustic matching layer, and
• the transmission member transmits the repeat deformation of the acoustic matching layer to the vibration member.