A pattern forming method is provided for forming a pattern of a multilayer film including insulative films and electrically conductive films stacked together and having a hole formed therein on a substrate with the electrically conductive film being selectively accurately indented from an inner peripheral surface of the hole. The pattern forming method includes the steps of: alternately stacking at least two insulative films and at least two polysilicon films on a substrate to form a multilayer film including the at least two insulative films and the at least two polysilicon films; forming a hole extending through the at least two insulative films and the at least two polysilicon films in the multilayer film; and selectively etching the polysilicon films from a side wall of the hole through isotropic etching by feeding into the hole an etching gas prepared by diluting fluorine-containing halogen gas with an inert gas.