A sit-up exerciser has a base, a seat and a footrest assembly mounted on the base, and a linkage assembly mounted between base and the seat. The linkage assembly has a handle arm, a back arm and a linking rod connected to each other. At least one rear resilient element is connected between the seat and the back arm and at least one front resilient element is connected between the footrest assembly and the handle arm. The resilient elements assist in performing sit-ups and the back arm supports a neck and vertebral column to prevent injury and damage.