The present invention concerns a method of forming one or more thin films on a substrate by depositing two or more materials by vacuum evaporation, comprising, depositing each material under such control that ni value of the each material is k0.5 wherein k is a constant from 2 to 5, when relationship between a deposition position and a film thickness of a material i on the substrate is approximated by the following equation (1):

D_i/D_0i(L₀/L_i)³cosⁿⁱ_i  (1)

wherein L₀ is a distance from an evaporation source to a plane of the substrate in a perpendicular direction, D_0i is a film thickness of the material i at an intersection point of a perpendicular line from the evaporation source to the plane of the substrate, and D_i is a film thickness of the material i at a position on the substrate which is apart from the evaporation source by a distance L_i in a direction of an angle _i against the perpendicular line. By the method, a homogenous thin film layer for an element can be formed even on a substrate having large screen.