In the present study, the vacancy concentration of pure cobalt was investigated by measuring the resistivity. The discontinuity of resistivity increase was appeared near the transition point. The vacancy formation energy was determined as E_f=0.99 ev (the vacancy formation energy of the sample quenched from the temperature below the transition point). The moving energy of vacancy was calculated as E_m=0.43 ev (the vacancy moving energy of the sample quenched from 711°K).