The two‐dimensional characterization of the Au/Ni/thin p + ‐GaN/n − ‐GaN structure, which is a part of a junction barrier Schottky structure, is demonstrated by scanning internal photoemission microscopy (SIPM) method. In the SIPM photoyield image using a blue laser, small photocurrents based on the internal photoemission effect by electron injection across the metal/semiconductor interface (from Ni to GaN) are detected in the center of the electrode. On the periphery, large photocurrents in the opposite direction are detected. These currents are caused by the hole injection from Ni into p + ‐GaN layer and the electrical field in the laterally extended depletion layer at the edge. By using a violet laser, large photocurrents based on the fundamental absorption generated in the depletion layer of the n − ‐GaN layer are uniformly detected over the electrode. It is conformed that SIPM can be available for quasi‐three‐dimensional characterization of this structure.