To provide a regulation method for a magnified image of a corneocyte capable of comparison with the observation results in the past, while shortening the staining time in a method for staining the corneocyte and for preparing a corneocyte sample, capable of giving information useful for differentiating a skin conditions and for properly selecting cosmetic substances.

The corneocyte sample collected from the skin is stained by an instantaneous dye solution, containing a dye, an aromatic alcohol and an organic acid, of which the 1-4C alcohol content is 50 mass% or lower, the corneocyte is fetched as the magnified image, and color is regulated by CG to regulate the magnified image of the corneocyte.