A coating method in which a surface of a web 7, which is supported by a pair of support rolls 2 and 3 so as to run continuously along a back edge surface 4 and a doctor edge surface 5 of a coating head 1, is coated with a coating composition by the coating head 1. The coating method includes setting an optimum coating condition by adjusting the distance b from a top end portion 10 of a slot 6 to each of the points of tangency 8 and 9 where the web 7 contacts the respective support rolls 2 and 3 on the basis of a relation expression under the consideration of the thickness t, Young's modulus E and Poisson's ratio .nu. of the web 7, the deviation .delta. of rotation due to the eccentricity of each of the support rolls 2 and 3, and the carrying tension T per unit width of the web 7; and extruding the coating composition continuously from the top end portion 10 of the slot 6 of the coating head 1 to the surface of the web 7. Accordingly, a good coating method is provided in which a uniform coating layer can be obtained on the basis of the clarification of a coating condition in which a coating composition is applied onto a thin web without the occurrence of any stripe irregularity and/or any thickness irregularity.