(a) Forming on a growth substrate a void-containing layer that is made of a group III nitride compound semiconductor and contains voids. (b) Forming on the void-containing layer an n-type layer that is made of an n-type group III nitride compound semiconductor and serves to close the voids. (c) Forming on the n-type layer an active layer made of a group III nitride compound semiconductor. (d) Forming on the active layer a p-type layer made of a p-type group III nitride compound semiconductor. (e) Bonding a support substrate above the p-type layer. (f) Peeling off the growth substrate at the boundary where the void are produced. (g) Planarizing the n-type layer. Step (b) comprises (b1) forming part of the n-type layer under conditions where horizontal growth is relatively weak and (b2) forming the remaining part of the n-type layer under conditions where horizontal growth is relatively strong.