Disclosed is a method for forming patterns that can improve line width roughness (LWR) by forming a first resist material on an etch target layer, forming a second resist material including a light-shielding portion and a light-transmitting portion on the first resist material, exposing the first resist material using the light-shielding portion of the second resist material as an exposure mask, removing the second resist material, forming a first resist pattern by developing the exposed first resist material, and etching the etch target layer using the first resist pattern as an etch barrier.