Provided are a p-type electrode and a III-V group GaN-based compound semiconductor device using the same. The electrode includes a first layer disposed on a III-V group nitride compound semiconductor layer and formed of a Zn-based material containing a solute; and a second layer stacked on the first layer and formed of at least one selected from the group consisting of Au, Co, Pd, Pt, Ru, Rh, Ir, Ta, Cr, Mn, Mo, Tc, W, Re, Fe, Sc, Ti, Sn, Ge, Sb, Al, ITO, and ZnO. The Zn-based p-type electrode has excellent electrical, optical, and thermal properties.