To provide a seat belt retractor and a seat belt apparatus in which contact between a locking base and a base frame can be suppressed. A seat belt retractor includes a spool 2 that retracts a webbing restraining an occupant, a base frame 3 that accommodates the spool 2 while allowing the spool 2 to rotate, and a lock mechanism 4 regulating rotation of the spool 2. The lock mechanism 4 includes a locking base 41 disposed at an end portion of the spool 2, an opening 31 that is formed in the base frame 3 and allows the locking base 41 to be inserted therethrough, engagement teeth 32 formed at an inner edge of the opening 31, and a pawl 42 that is disposed radially outwardly movable relative to the locking base 41 and engageable with the engagement teeth 32. The lock mechanism 4 further includes a protect cover 43 that is attached to the locking base 41 and includes a side wall portion 43b disposed along a side surface portion of the locking base 41.