To eliminate an influence exercised on a work due to dust when an existing deteriorated pipe is axially cut by a cutter.

The dust collecting device comprises a blast means to effect blast means to effect blast of an amount of equivalent to a dust absorbing amount of dust generated in the line 2 in the direction of one end of the line 2 when a buried pipe 5 is cut by moving a cutting device from a shaft 3 built on one end side of a buried line 2 to be renewed toward a shaft 4 on the other end side; and a dust collecting means 11 situated at one end of the line 2 and sucking and collecting dust.