Ultrasonic device and medium transport device

A medium transport device that transports a medium, the medium transport device comprising:

• an ultrasonic transmission unit including:
• a medium transport path through which the medium is transported;
• an ultrasonic element arranged spaced apart from the medium transport path and transmitting an ultrasonic wave;
• a wiring arranged at a transmission surface outer circumference of a transmission surface of the ultrasonic element and coupled to the ultrasonic element;
• a shield covering the wiring, the shield having a shield opening that faces the transmission surface and through which the ultrasonic wave passes;
• a protector facing the transmission surface of the ultrasonic element and being formed of a porous material through which the ultrasonic wave passes;
• a holder covering the shield via a space therebetween, the holder having a holder opening that faces the transmission surface and through which the ultrasonic wave passes;
• and
• a circuit board having a surface with which the ultrasonic element, the shield, and the wiring are supported,
• wherein the protector is arranged at the holder opening, and
• a width of the holder opening is larger than a width of the transmission surface in a plan view.