A fall arrest device includes a bracket, a rotating member rotatably mounted to the bracket, a safety belt wound around the rotating member, a brake wheel connected to the rotating member, a brake block pivotally connected to the brake wheel, and a restoring spring fitting around the second segment and having one end thereof terminating in a ring that has an inner diameter smaller than an outer diameter of the first segment. Another end of the restoring spring is connected to the brake block. The brake wheel has a fixed rod having a first segment and a second segment. An outer diameter of the first segment is greater than an outer diameter of the second segment. The restoring spring urges the brake block to be located in a restoring position. Thus, the restoring spring could be prevented from falling out of the fixing rod.