According to one embodiment, a method is disclosed for manufacturing an integrated circuit device, the method can include forming a mask member on a first film, the mask member having a pattern, performing a first etching on the first film using the mask member as a mask to form a recessed section in the first film, forming a second film covering an inner side surface of the recessed section. The second film has a film thickness of preventing blockage of the recessed section, and performing a second etching on the second film and the first film via the recessed section. The performing of the second etching includes performing a third etching in a condition of an etching rate at a place smaller in curvature radius in the recessed section being lower than an etching rate at a place larger in curvature radius in the recessed section.