An Ohmic electrode structure comprising a p-conductivity-type boron phosphide-based semiconductor layer containing boron and phosphorus as constitutional elements and having a surface; and an electrode disposed on said surface of said semiconductor layer and having an Ohmic contact with said semiconductor layer, wherein at least a surface portion of said electrode which is in contact with said semiconductor layer is formed from a lanthanide element or a lanthanide element-containing alloy. A compound semiconductor light-emitting device comprising a light-emitting layer formed of a compound semiconductor may advantageously comprise the Ohmic electrode structure.