An object of the invention is to propose a tubular structure and a wind turbine generator in which work on an outer surface of the tower structure can be performed easily. A tubular structure comprises: a plurality of tubular sections 21 that are stacked one on top of another in a vertical direction, the adjacent tubular sections 21 being joined together with use of a splice plate 22 arranged on at least one of an inner surface and an outer surface of abutting ends of the adjacent tubular sections 21 and a fastening member 25 fastening the splice plate 22 and the adjacent tubular sections 21; an opening for operation 26 which is arranged in a vicinity of the splice plate 22 on a circumferential surface of the tubular sections 21; and a reinforcing rib 28 arranged in the vertical direction on the circumferential surface of the tubular sections 21, wherein a vertical position of the reinforcing rib 28 includes at least a vertical range where the opening for operation 26 is arranged.