A sit up exercising apparatus has a seat assembly, an actuating bar The seat assembly has front leg, a cushioned seat and a rear leg. The actuating bar is attached pivotally to the seat assembly and provides an elastic force to assist a person using the sit up exercising apparatus and has multiple rollers. The rollers massage a person's back who is using the sit up exercising apparatus. Consequently, a person's backbone is not likely to be injured, and the exercising force can be adjusted to accommodate individual users based on their age or physical condition.