PURPOSE: To provide a low resistance collector electrode of uniform height and its forming method by restaining a lump which is generated at the time of forming a solder layer of the collector electrode.

CONSTITUTION: In a method of forming an electrode wherein a collector electrode is formed on a transparent electrode 4, a conducting layer having a wettability with soldering material is formed in a desired shape on the transparent electrode 4, soldering material is formed so as to cover the conductive layer, a part member having flatness at a solder fusion temperature is mounted on the upper surface of the soldering material, and, in this state, the soldering material is fused and solidified to obtain a solder layer 3 having a flat surface.