PROBLEM TO BE SOLVED: To provide a method capable of simply and highly accurately managing the state of a membrane formed even in a case where the density and dry state of a substrate are different.SOLUTION: In a management method of a membrane, coating liquid containing at least solid particles, a liquid component, pigment particles insoluble in the liquid component and a pigment soluble in the liquid component is applied to a substrate surface, and the state of the membrane is determined from the color of the formed membrane. The state of the membrane can be determined by optically detecting fluctuation of abundance ratio before and after coating of the pigment particles insoluble in the liquid component and the pigment soluble in the liquid component.
