Oil from Nigella sativa seed has been extracted by supercritical CO2 as a solvent at various pressures. In this study, two conditions of separation were used; they were low and high pressure separation. The antioxidant activity of the oil extracted was measured using an ultraviolet-visible spectrum (UV-Vis) spectrophotometer. There was no effect on the change of extraction pressure in apparatus with low pressure. The essential oil content in the extract from apparatus with high pressure was approximately two times higher than it was with low pressure. The antioxidant activity of Nigella sativa oil showed positive result. The antioxidant activity was obtained by the quantity of thymoquinone and carvacrol.