A method for forming a sealing film, in which a buffer layer and a barrier layer whose density is higher than that of the buffer layer are alternately formed on a substrate, includes forming a first buffer layer on a surface of the substrate, forming a first barrier layer on a surface of the first buffer layer, and forming a second buffer layer on a surface of the first barrier layer. A ratio of a thickness of a portion of the first buffer layer in a thickness direction of the substrate relative to a thickness of a portion of the first buffer layer in an inclined direction that is inclined with respect to the thickness direction is closer to 1 than a ratio of a thickness of a portion of the second buffer layer in the thickness direction relative to a thickness of a portion of the second buffer layer in the inclined direction.