Proposed are a layered Group III-V compound containing phosphorus, a Group III-V nanosheet that may be prepared using the same, and an electrical device including the materials. There is proposed a layered compound represented by [Formula 1] Mx-mAyPz (Where M is at least one of Group II elements, A is at least one of Group III elements, x, y, and z are positive numbers which are determined according to stoichiometric ratios to ensure charge balance when m is 0, and 0