To easily damp vibration of wide frequency domains and secure durability.

This damping addition device 20 having an opening portion 22 open to a combustion region 12 of a combustion chamber 11 and a plurality of resonance spaces 25 is mounted on the combustion chamber 11. Only one of the plurality of resonance spaces 25 is connected to the opening portion 22. On-off valves 50 are provided between the plurality of resonance spaces 25. When fuel is burnt in the combustion region 12, combustion vibration may occur, but the vibration enters from the opening portion 22 into the resonance spaces 25 where it is resonated and damped. The combustion vibration includes a plurality of frequency domains, but when the on-off valves 50 are opened/closed, the capacities of the resonance spaces 25 for resonating the vibration are changed to damp the vibration of the frequency domains corresponding to the capacities. As a result, the vibration of the wide frequency domains is easily damped and durability is secured.