To provide a film forming method which enables the manufacture of a color filter with the distribution of film thicknesses of the film improved further with a slit-and-spin coater.

The distribution of film thicknesses of the coating film, coated with a slit coater, is such as to be thin at one end of the substrate, become thicker gradually toward the center of the substrate and become thinner gradually toward the other end of the substrate. The distribution is based on the relationship between the predetermined distribution of film thicknesses of the coating film after rotation with the spin coater and that of the coating film coated with the slit coater.