A manufacturing method of a semiconductor device includes forming a hard mask layer and a photoresist on a substrate having a layer to be etched, and performing exposure and development such that the patterned photoresist has first trenches and to expose the hard mask layer, wherein ends of the first trenches have a width gradually decreased toward an end point. The exposed hard mask layer is removed using the patterned photoresist to transfer the pattern of the first trenches to the hard mask layer such that the patterned hard mask layer has second trenches, and the ends of the second trenches have a width gradually decreased toward an end point. Spacers are formed on inner walls of the second trenches. The hard mask layer is removed such that the layer to be etched is exposed. The exposed layer to be etched is removed using the spacers as an etch mask.