ULTRASONIC SENSOR

The ultrasonic sensor includes a wave transmitting and receiving device and a cover. The wave transmitting and receiving device has a front surface including a wave transmitting and receiving surface and is configured to transmit and receive an ultrasonic wave through the wave transmitting and receiving surface. The cover covers the wave transmitting and receiving device so as to expose the wave transmitting and receiving surface. The cover is constituted by multiple portions, and the multiple portions are individually made of multiple materials different from each other.