To demonstrate uniform slip performance no matter from which direction and at which part a vehicle arrives, regarding a circular lid for an underground structure which blocks a circular opening connected to an underground structure and provided on a ground surface at the same height position as the ground surface.

The circular lid for an underground structure includes a plurality of first projection bodies 10c that are arranged along a plurality of radial straight lines RS1 extended in a radial direction at an interval in a circumferential direction R from a center O of the circular lid for the underground structure and have a polygonal projected tip surface projected upwards, and the first projection bodies 10c are arranged so as to turn a longitudinal direction W to a direction orthogonal to the radial direction R.