A sensor electrode has an upper side portion arranged on an automobile, a lower side portion arranged with a predetermined spacing from the upper side portion, and a connecting portion that connects the upper side portion and the lower side portion. A control unit inputs a signal for detecting a user to the upper side portion, the lower side portion, and the connecting portion, which are electrically connected. The lower side portion is arranged farther from an area through which the user passes than the upper side portion. The installation height of the upper side portion is greater than or equal to the installation height of the lower side portion.