The present invention relates to a safety belt retractor, including a bracket, a spool, a locking device, a vehicle sensing device with an adaptive vehicle sensing function and a vehicle sensing adaptivity suppression device. The vehicle sensing adaptivity suppression device includes a driven part (8) and a suppression part (7) that can be held on the driven part by an adhesive force. The driven part has a sliding track, and the suppression part has a sliding portion which can slide on the sliding track against the adhesive force. The suppression part has a retainer, and a sensing seat has a counter retainer that cooperates with the retainer. A retaining connection isn't formed when the suppression part is in the first end position, and is formed when the suppression part leaves away from the first end position to a predetermined extent. Here, the mechanism for achieving the vehicle sensing adaptivity suppression function is simple in structure and low in cost, and can effectively suppress the adaptivity of the vehicle sensing function. The present invention further relates to a safety belt assembly comprising such a safety belt assembly.