An abdominal exercise device has a base, a seat mounted on the base, a front frame rotatably on a front of the base, a rear frame rotatably mounted on a rear of the base, a connecter connected pivotally to the front frame and the rear frame, an adjusting assembly mounted on the base and at least one resilient element connected to the rear frame and adjusting assembly. The at least one resilient element pulls the rear frame along with the connecter and the front frame to assist in performing sit-ups so abdominal muscles of a user using the abdominal exercise device is trained.