Abstract: A driven mechanism for a rotatory heat regenerator, in which a shock absorbing member is fitted around the outer peripheral surface of a discoidal rotatory regenerator having a honeycomb structure. A metal ring having teeth is set around the outer periphery of the shock absorbing member and held in position thereby. The ring is driven by at least one driving gear connected with a prime mover and transfers torque to the rotatory regenerator. Torque fluctuations on the driving gear are moderated by the elastic deformation of the ring and the shock absorbing member. Any difference in the amount of thermal expansion between the ring and the regenerator is compensated by the shock absorbing member.