Diamond is grown on a substrate (S) from a mixture of a carbon-containing gas and hydrogen gas, by a DC plasma enhanced CVD process of applying a DC voltage between a stage electrode (12) for holding the substrate (S) and a voltage-applying electrode (13). During the step of growing diamond by applying a DC voltage, a single pulse voltage of opposite polarity to the DC voltage for diamond growth is applied between the stage electrode and the voltage-applying electrode at a predetermined timing. Diamond of quality is produced at a stable growth rate.