Provided are a seat belt retractor and a seat belt device capable of suppressing an increase in frictional resistance when a pretensioner is steadily driven and increasing the resistance to be applied to a webbing when energy is absorbed. A seat belt retractor includes a guide member facing at least a part of an outer circumferential surface of a locking base and disposed along an opening portion. The guide member is configured not to come into contact with the locking base until a pretensioner is shifted to a steady driving state, is configured to come into contact with the locking base when the pretensioner is steadily driven, and is configured to allow contact between lock teeth and the locking base when subjected to a predetermined load after the pretensioner is shifted to the steady driving state.