An ultrasonic sensor includes a support body having an opening, a support film closing the opening, a piezoelectric body disposed on the support film in an inner region of the opening in a plan view, a first resin material forming a first space closed off from an outside space between the first resin material and the support film in at least a region in which the opening is formed in the plan view and the first resin material having an contacting portion facing the opening and being configured to contact with a test object, a second resin material forming a second space closed off from the outside space and communicating with the first space, and an ultrasonic wave transmitting medium filling the first and second spaces. A flexible portion having lower rigidity than the support film in the film thickness direction is provided in a portion of the second resin material.