According to one embodiment, a method for manufacturing an LED device includes forming a laminated semiconductor layer including a GaN layer of a first conductivity type, a GaN-based luminous layer, and a GaN layer of a second conductivity type stacked in this order on a surface of a substrate, forming a resist pattern on the laminated semiconductor layer, subjecting the laminated semiconductor layer to reactive ion etching using the resist pattern as a mask to selectively remove the laminated semiconductor layer to form an LED element structure part and an electrode connection region, removing the resist pattern, and treating the substrate including the LED element structure part and the electrode connection region with a first etching residue removing aqueous solution.