An incision is formed at a site where a cellular tissue is to be dissected. A liquid is ejected to the incision. The incision is expanded. The cellular tissue is dissected. The liquid is ejected in the form of a pulse flow. The liquid is ejected in such a way as to advance obliquely to a tangential direction to a surface of the cellular tissue. A site where the liquid is applied to the surface is moved in a direction in which an angle formed by the surface and the direction of advancement of the liquid is greater.
