US Patent 11374566 Motion detection device

A motion detection device includes an attached member on a vehicle body side, a sensor electrode configured to detect capacitance, and a sensor bracket. The sensor bracket has a sensor holding portion holding the sensor electrode and is attached to an inner surface of the attached member. The sensor holding portion includes a holding piece that extends from a side away from an inner surface of the attached member to a side approaching the inner surface and holds the sensor electrode, and the holding piece holds the sensor electrode at a position at which an axis of the sensor electrode is separated from the inner surface of the attached member by at least 15 mm or more.