A thermal storage type gas treating apparatus has a high sealing performance while achieving a simple apparatus construction. The thermal storage type gas treating apparatus includes a valve member rotatable to place successively a supply port for a gas to be treated and an exhaust port for a treated gas formed in the valve member, in an opposed and communicating relationship with supply and exhaust ports formed in a distributor, thereby successively passing gas to be treated and treated gas through a plurality of thermal storage chambers communicating at one end with a combustion chamber. The valve member is supported to be displaceable toward and away from the distributor. A valve biasing device is provided for pressing the valve body to the distributor, while being inoperative with respect to a gas chamber device.