PURPOSE: To enhance painting workability by injecting compressed air from the emitting orifice in the vicinity of the liquid substance jet orifice of a spray apparatus so that a curing promoting agent is not brought into contact with the jet orifice.

CONSTITUTION: A liquid substance (e.g. two-pack type urethane resin paint) cured at room temp. in the presence of a curing promoting agent (e.g. amine vapor) is subjected to spray painting. At this time, a carrier gas stream containing the curing promoting agent is mixed with the spray of the liquid substance and the resulting mixture is brought into contact with an object to be painted to form a film on the object to be painted. Further, in order to prevent that the curing promoting agent of an emitting orifice 3 is brought into contact with the jet orifice 1 of the liquid substance of a spray apparatus, compressed air is injected from the emitting orifice 2 in the vicinity of the jet orifice 1. As a result, a liquid rapidly cured can be applied without generating clogging of a nozzle or the generation of foreign matter in a film and painting workability can be enhanced.