An etching liquid for a multilayer thin film that contains a copper layer and a molybdenum layer, andthe method for etching a multilayer thin film are provided. The etching liquid is obtained by blending (A) an organic acid ion supply source that has two or more carboxyl groups and one or more hydroxyl groups in each molecule, (B) a copper ion supply source and (C) an ammonia and/or ammonium ion supply source. The etching liquid has a pH of 5-8. Besides, the etching method of using the etching liquid is provided.