Abstract: A sacrum support device for use by individuals when performing sit-up exercises provides a protective flexible rubber pad. In a first embodiment, the pad is supported between a waist encircling strap and a pair of leg encircling straps by two pairs of support straps. The pad has a pentagonal shape with a downwardly pointing apex and is positioned over the sacrum of the individual. In a second embodiment, briefs formed from a washable fabric material are provided with a rear pocket for insertion of the pad. The pocket and pad may have a generally triangular or rectangular shape. The device provides protection for the sacrum or tail bone which is frequently irritated by repeated sit-up exercises.