The utility model provides an attach cover locking device (10) that connect to vehicle (1), cover locking device (10) include casing (11) and locking component (20), and this locking component includes: main shaft part (21), from mid portion (25) that main shaft part is extended and from mid portion extend and the top end part (28) thinner than the main shaft part, the locking component setting is in the casing and can follow the axial direction removal, and wherein, at least, top end subtotal mid portion sets up the outside at the casing, wherein, mid portion constructs and narrows down towards top end part side from main shaft part side, and mid portion is provided with at least one inclined surface, at least one inclined surface follows the direction downward sloping in the outside on vehicle width direction towards the vehicle and incline to the central axis along the direction towards the top end part.