To provide a gas turbine premixing pipe structure that generates a uniform and satisfactorily diluted mixed gas when generating a mixed gas of combustion gas and air.SOLUTION: Air holes 1a1, 1a2, 1a3 and 1a4 are formed in a cylindrical body portion 1a of a premixing pipe 1. The number of air holes 1a1 formed on the most upstream side is made larger than the number of other air holes 1a2, 1a3 and 1a4. The air holes 1a2, 1a3 and 1a4 are formed in zigzag positions to each other. The downstream side of the body portion 1a is an inclined pipe portion 1e continuous with a conical body portion 1c narrowed so as to have a gradually smaller diameter. An opening 1d is provided so as to face a central portion of an inner cylinder of a combustor, and a mixed gas is jetted toward a flame by a pilot fuel.SELECTED DRAWING: Figure 1