PURPOSE: To certainly perform coating along a desired route in an existing pipe, in repairing said pipe, by sucking carrier gas into the pipe with large negative pressure to put directionality to the stream of the carrier gas.

CONSTITUTION: One end of an existing pipe A is connected through a recovering device 1a and a conduit 1b for suction to the inlet side of a vacuum pump 1, while the other end is connected to a device 2 for forming an air stream. Thus, carrier gas is affected by negative pressure and moved through the existing pipe A. Since the pressure of the carrier gas itself is small, the spreadability of a coating agent adherent to the inner wall of the existing pipe A is made high. In addition, the carrier gas in a state supporting the coating agent can be conveyed as such over a relatively long distance, and the coating can be performed along a desired route since the flow of the carrier gas is determined.