The present invention is characterized by comprising: a rear hinge excavated unit which is mounted on the upper surface of the outer circumference of a manhole frame, and is opened from one side towards an upper side; a hinge frame in which a rear hinge moving elongated hole is provided at both sides to be moved forwards and backwards and vertically rotated; a rear hinge which is mounted on the rear hinge excavated unit of the hinge frame, wherein a rear hinge pin of a pin shape is connected to one side thereof to be vertically rotated while being moved forwards and backwards after being inserted into the both sides of the rear hinge moving elongated hole, and a front hinge moving elongated hole is provided at the other side thereof to be moved in back-and-forth directions while being vertically rotated; and a front hinge which is fixated to the upper side of a manhole cover, and to which a front hinge pin of a pin shape is connected to be moved frontwards and backwards while being vertically rotated after being inserted into the front hinge moving elongated hole of the rear hinge to open and close the manhole cover. Therefore, the present invention can be provided at one side of a manhole frame mounted on an opening unit of a sewage pipeline to be fastened at the identical height as the ground surface without being exposed to the outside so as to be mounted to prevent interruption in the passage of passersby or vehicles. Furthermore, the two-step hinge unit connected to the manhole frame is linked with the opening of a manhole cover to be moved in back-and-forth directions and vertically rotated to be completely opened at 180 degrees. Consequently, the manhole cover can be easily opened in a two-step manner without being interrupted during the opening process.

본 발명은 맨홀프레임의 외주연 상면에 안착되며 일측에서 상측으로 개방된 후방힌지요입부와, 양측에 전후로 이동되고 상하로 회전되도록 후방힌지이동장공이 형성된 힌지프레임과, 상기 힌지프레임의 후방힌지요입부에 안착되며, 일측이 상기 후방힌지이동장공의 양측에 삽입되어 전후로 이동되면서 상하로 회전되는 핀형상의 후방힌지핀이 연결되고, 타측이 전후이동되면서 상하로 회전되도록 전방힌지이동장공이 구비된 후방힌지와, 상기 맨홀덮개의 상측에 고정되며, 상기 후방힌지의 전방힌지이동장공에 삽입되어 전후로 이동되고 상하로 회전되는 핀형상의 전방힌지핀이 연결되어 맨홀덮개를 개폐시키는 전방힌지로 구성된 것을 특징으로 하여, 하수관로의 개구부에 안착되는 맨홀프레임의 일측에 외부로 노출되지 않고 지면과 동일한 높이로 체결하여 보행자나 차량이 통행 할 경우 간섭을 받지 않게 장착할 수 있고, 맨홀프레임에 연결되는 이단힌지부가 맨홀덮게의 개방과 연동하여 전후로 이동되고 상하로 회전되어 180도 완전히 개방할 수 있고, 개방시 전혀 간섭받지 않고 이단으로 맨홀덮개를 용이하게 개방할 수 있는 효과가 있다.