Strawberries are one of the most popular fruits in Japan and they have a high antioxidant content. In this study, the contents in strawberry receptacles were extracted with supercritical carbon dioxide and entrainers. Using ethanol, acetone, and water as entrainers improved the antioxidant capacity and increased the amounts of total saccharides and cinnamic acid in the extract. In supercritical carbon dioxide + ethanol, the extract yield increased slightly with increasing pressure up to 20 MPa at 313 K whereas the extract yield was almost constant against temperature. The amounts of total saccharides and cinnamic acid increased with increasing temperature and pressure. The antioxidant capacity increased, and then decreased with increasing temperature at 20 MPa and increasing pressure at 313 K. The optimal conditions for antioxidant capacity were 313 K and 20 MPa.