To provide a structure of a kick sensor which prevents a capacitive sensor from getting wet with rain water entering a rear surface of a rear bumper to prevent incorrect operation and which can be attached with easy operation, and to provide an attachment structure of the kick sensor.SOLUTION: A structure of a kick sensor includes a kick sensor case formed in a thin box shape elongated in a lateral direction. The kick sensor case includes: a sensor insertion groove which forms a recessed part extending along both longitudinal side surfaces and houses a capacitive sensor; and a waterproof gutter which is provided protruding in two directions along the side surfaces of the kick sensor case, facing a rear end of a rear bumper of a vehicle, so that its cross section is formed in a V shape and which extends in a manner that a center part is located high and both ends are located low when viewed in a longitudinal direction. The kick sensor case is configured to house the capacitive sensor inserted into the sensor insertion groove and a sensor signal processing part which detects kick operation by a signal from the capacitive sensor.SELECTED DRAWING: Figure 7