A connector has a bottom wall located at a lower portion in an attached state in which the connector is attached to an ultrasonic diagnostic device body. The bottom wall has a ventilation portion having a plurality of openings and a non-ventilation portion adjacent to the ventilation portion. The bottom wall has an inner step that functions as a weir structure for restriction of movement of liquid from an inner face of the non-ventilation portion to an inner face of the ventilation portion in the attached state. An outer face of the bottom wall is provided with an outer step corresponding to the inner step.
