According to one embodiment, an etching method includes: supplying an etching-resistant material; and etching the silicon nitride film. The supplying includes supplying the etching-resistant material to a processing surface including a surface of a silicon nitride film and a surface of a non-etching film, the non-etching film including a material different from the silicon nitride film. The etching includes etching the silicon nitride film using an etchant in a state of the etching-resistant material being formed relatively more densely on the surface of the non-etching film than on the surface of the silicon nitride film.