To provide a catalyst device capable of reducing the cost of a catalyst that cleans combustion gas throughout ignition, combustion and extinction.

A catalyst device 1 is provided with a cloth catalyst body 2 of a comparatively small heat capacity, having holes which allow combustion gas to pass, a metal frame 3 which holds this cloth catalyst body 2, and stainless rods 4 of a comparatively large heat capacity, which are attached to the metal frame 3, heated by the combustion gas, and warms the cloth catalyst body 2 with remaining heat when extinguished.