LID DEVICE

A lid device (1) mounted on an oil filler port (3) or an power supply port of a vehicle and for opening and closing the oil filler port (3) or the power supply port includes: a housing (10) configured to be assembled to the oil filler port (3) or the power supply port; a support body (21) provided to be rotatable with respect to the housing (10); and a lid body (41) attached to the support body (21). Reinforcing ribs (27, 28) protruding toward a lid body (41) side are formed on the support body (21), and in a state in which the lid device 1 is mounted on the oil filler port (3), a portion of the reinforcing ribs (27, 28) along a horizontal direction is inclined such that free end sides face downward.