To provide a lid structure of an oil filler port capable of preventing a danger that oil leaks and facilitating opening and closing control by the simple structure.

The oil filler port 12a in an end part of an oil supply pipe 12 communicating with a fuel tank of an automobile faces an opening part 11a on a surface 11 of a car body, and an oil filler port cap 15 having a valve 13 opened when pressed by a cylinder tip 17 of an oil supply nozzle from the outside is attached to the oil filler port 12a. An oil filler port lid 20 which is brought into contact with an end face of the oil filler port cap 15 and is closed and whose outer face is positioned on the same face as the surface 11 of the car body in a closed condition is attached to the vicinity of the opening part 11a on the surface 11 of the car body so as to turn freely, and a seal member 24 is provided in a part opposing to the end face of the oil filler port cap 15 in a condition in which the oil filler port lid 20 is closed.