[PROBLEM TO BE SOLVED] To provide a method and apparatus for applying a coating material that reacts at ordinary temperatures and increases in viscosity with lapse of time or a coating material that is difficult to handle, such as an unstable slurry in which sedimentation occurs at high rate, to a high-value-added object to be coated. [SOLUTION] Before at least applying coating material to an object to be coated, the coating amount is automatically measured using a highly-accurate measuring device set in an atmosphere that does not substantially affect the measurement to control the coating amount during production. Therefore, high-quality products can be mass-produced with a low production cost.