Abstract: A common method of preparing a gas diffusion layer for a fuel cell has problems in that a microporous layer is impregnated into a substrate, thereby lowering the porosity of the substrate, and cracks are created on a surface of a gas diffusion layer prepared using the method. Provided is a method of reproducibly preparing a gas diffusion layer with a uniform thickness and no cracks based on the principle of a primer coating method, wherein a first microporous layer is hardly impregnated into a substrate and uniformly covers a surface of the substrate, and at least one microporous layer is further coated on the first microporous layer. Provided is also a fuel cell showing improved performance by enhancing utilization of a catalyst layer and guaranteeing a uniform diffusion of fuel and an efficient discharge of a product.