To provide the connection method of a double pipe and equipment capable of easily and exactly connecting the inside pipe and the outside pipe, and maintaining the aligned center axes of the connected members.

The inside pipe is composed of the connected inside pipe unit 10 which has male flange 12 and female flange 14 fixedly connected with the edge of mud pipe, water pipe, and air pipe respectively. The structure of this equipment is to connect the mud pipe edge 20T projecting from one of male flange 12 of one inside pipe unit 10R to be connected is fitted to with the opening 20H formed at female flange 14 of other inside unit 10L. The edge of a water pipe 24T and/or an air pipe 22T projecting from male flange 12 of inside pipe unit is fitted with the openings 24H, 22H formed at female flange 14 of the other inside pipe unit. Thereafter, the inside pipe moves counterclockwise to connection portion 16S by pushing joining metalic parts 16 of inside unit 10L by utilizing the edge 30E of other outside pipe 30L.