A wide slit nozzle having a slit as a discharge opening. The thickness of a lateral end part is set smaller than the thickness at a lateral center part. The thickness of the lateral center part is fixed. The thickness of the lateral end part changes linearly from opposite lateral ends of the lateral center part to the opposite lateral ends of the slit. Coating material is discharged from the slit while applied with pressure, so that the coating material is coated while expanded wider than the width of the slit. The coating material is discharged at 7 liter per minute, and a coating width of a first example is 100 mm, for example. A thickness increase of the overlapped part is +25% even when a width or an overlapped margin z of the overlapped part is 10 mm or 20 mm.