We developed the Biased Double D. C. Arc Plasma apparatus and synthesized diamond thin films on silicon wafer using it. We named this process Biased Double Arc Plasma CVD process (B. D. A. Plasma CVD). It was possible to obtain a high growth rate of diamond films because of the effective decomposition of reactant by applying bias voltage between plasma and substrate and also, the degree of freedom of the selection of reaction conditions to get a good diamond films was broadened compare with the HFCVD on MWCVD process.