To increase the water flow sectional area of an existing line as a current water flow is ensured, to renew a deteriorated existing line, and to provide an increased life for a line.

A fixed type water cutoff device 3 and a moving type water cutoff device 4a are arranged in the given position of a sewer pipe 1, and the devices are intercoupled by management pipes 7, 7... through a valve 11 for controlling a water flow. With the valve 11 for controlling a water flow temporarily closed, the moving type water cutoff device 4 is advanced to a spot situated downstream of a line and the control pipes 7 are connected in a given position in series to a control pipe train, Thereafter, according to a procedure to open the valve 11 for controlling a water flow, a management section for sewage is extended. Meanwhile, in a space nipped between the fixed water cutoff device 3 and the moving type water cutoff device 4, a secondary lining is removed simultaneously with advancing of the moving type water cutoff device 4, and consecutively a lining material 2 is applied on an inner wall surface after expansion.