An etching method for etching a silicon-containing layer into a pattern of a mask is provided. The mask is formed by etching, from a block copolymer layer that includes a first polymer and a second polymer, that is layered on the silicon-containing layer of an object to be processed via an intermediate layer, and that is enabled to be self-assembled, a second region including the second polymer and the intermediate layer right under the second region. The etching method includes generating plasma by supplying a process gas including carbon C, sulfur S, and fluorine F to the inside of a processing chamber of a plasma processing apparatus in which the object to be processed is provided; and forming a protective film on the mask and etching the silicon-containing layer according to the generated plasma.