This invention provides a p-type group III nitride semiconductor, with good p-type properties, having a composition expressed by AlXGaYInZN in which each of X, Y and Z indicates a rational number satisfying a relationship of X+Y+Z=1.0, even if Al content is as high as 1.0>X≧0.5. It is achieved that a proportion of a hole concentration at 30° C. to an acceptor impurity atom concentration is 0.001 or more in the p-type group III nitride semiconductor of the invention, by doping acceptor impurity atoms such as Mg in concentration of 5×1018 to 1×1020 cm−3 using the method, for example, MOCVD with attention not to incorporate an impurity atom other than the acceptor impurity atom or not to form dislocation in the crystal when producing the group III nitride semiconductor expressed by the above composition.