A tritium implantation method based on a glow discharge of tritium gas was applied to the measurement of diffusion coefficient of tritium in alpha-phase of zirconium. The diffusion experiment was carried out in a temperature region from 673 K to 873K, and the diffusion coefficient of tritium was determined as follows,The present data were in good agreement with our previous data which were determined with an usual implantation method based on a nuclear reaction6Li(n,α)T.