A pilot nozzle of a gas turbine combustor comprises a first structure, provided near a main nozzle of a combustor that injects fuel oil, having a flow channel for a fuel gas and an outlet for the fuel gas. The first structure diffusion-injecting the fuel gas obliquely forward through the outlet to maintain a flame and to aid ignition of the fuel oil injected from the main nozzle. There is further provided a second structure which circulates in whirls a combustion gas generated due to the combustion of the fuel gas.