PURPOSE: To obtain the subject coating agent applicable to a face left after removing an old asbestos layer without corroding the reinforcing steel, etc., constituting the application face by adding a flame-retardant to an emulsion of a polyacrylic acid ester.

CONSTITUTION: The objective coating agent is produced by adding a flame- retardant (e.g., hexabromocyclododecane) to an emulsion of a polyacrylic acid ester (preferably a copolymer of acrylic acid ester and methacrylic acid ester). The falling-off of the remaining small amount of asbestos from a face left after removing an old asbestos layer can be suppressed by spraying the agent onto the surface.