A combustion burner including a fuel nozzle, a burner tube that surrounds the fuel nozzle to form an air passage between the burner tube and the fuel nozzle, swirler vanes that are arranged in a circumferential direction on an external circumferential surface of the fuel nozzle, a liquid fuel injecting hole that is formed on the fuel nozzle, and from which a liquid fuel is injected to a vane pressure surface of each of the swirler vanes, and a cooling unit that cools a part of the vane pressure surface on which the liquid fuel hits. The cooling unit includes a multi-purpose injecting hole that is arranged on the vane pressure surface of each of the swirler vanes, and from which a gas fuel is injected during gas combustion, and water is injected to the vane pressure surface of the swirler vane during combustion of the liquid fuel.