To provide an energy absorbing device, a seat belt retractor, and a seat belt apparatus that can vary an energy absorbing amount depending on increase and decrease of rotation speed between relatively rotating objects and can improve durability. An energy absorbing device includes a casing connected to one object, an annular first clutch disc disposed in the casing, an annular second clutch disc disposed in the casing, and an annular clutch plate connected to the other object and having an engaging surface that faces both the first clutch disc and the second clutch disc, wherein the engaging outer teeth of the first clutch disc and the engaging inner teeth of the second clutch disc alternately engage with the engaging teeth of the clutch plate so as to absorb an energy generated by a relative rotation between one object and the other object.

To provide an energy absorption apparatus, a seatbelt retractor, and a seatbelt apparatus that are capable of changing the energy absorption amount according to increases and decreases in the rotation speed between objects that rotate relative to each other and capable of improving endurance. The energy absorption apparatus includes a first plate connected to one of the objects and having a wave-shaped groove formed in an annular shape, a second plate connected to another one of the objects, disposed so as to be adjacent to the first plate, and having a plurality of radial grooves formed at locations that face the wave-shaped groove, a plurality of driving pins that are inserted, at one end, in the wave-shaped groove and inserted, at another end, in the radial grooves, and a plurality of follower bodies that are housed in the wave-shaped groove or the radial grooves and that slide along the wave-shaped groove as the driving pins move.