In this paper, we detail the formation of carbide layers on refractory metals, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum and tungsten, using the electrical discharge machining (EDM) process. To form a carbide layer on a machined surface, a finishing EDM process with a scanning electrode was used. A carbide layer was formed on zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, but not tungsten. These layers have many microcracks and pinholes, but some layers exhibit good tribologiocal properties. The ratio of carbon to matrix in the carbide layers was lower than that in debris. Carburization may occur at different rates in the surface layer and debris, and carbon reacted rapidly with debris. Therefore, to form a carbide layer with a high carbon ratio, it was necessary to decrease generation of the debris under the EDM condition that allowed to carburization.