Paramagnetic defects in CVD (Chemical Vapor Deposition) diamond films were studied using the Electron Spin Resonance (ESR) method. Furthermore, the correlation between defects and electrical resistance of conductive layers on CVD the diamond surface were investigated using ESR and van der Pauw methods. An ESR center with g = 2.003, Delta H-pp=8 Oe, which is identical to the carbon dangling bonds in non-diamond phase carbon, is highly distributed with a spin density of 10(20) spinscm(-3) in the conductive surface layer. When thermal treatment was carried out in an oxygen atmosphere at 600 degrees C, the ESR center was removed and then the electrical resistance was at least 10(4) times greater than that of as-grown diamond films.