Abstract: An ultrasonic device includes an ultrasonic element configured to perform at least one of transmission of an ultrasonic wave along a first axis and reception of the ultrasonic wave input along the first axis, and a protective member provided on the first axis to cover the ultrasonic element. The protective member has a first surface provided with at least one hole through which the ultrasonic wave travelling along the first axis passes, and a second surface intersecting with the first surface and provided with a first opening through which foreign matter entering from the at least one hole is discharged.