Provided is a gas turbine combustor of a low cost. A main nozzle (3) for the gas turbine combustor comprises a cylindrical center tube (4) having an oil fuel passage (6), in which an oil fuel flows, a cylindrical outer tube (5) arranged in the outermost circumference, and a support tube (8) arranged between the center tube (4) and the outer tube (5), and those tubes are made independent of one another. The support tube (8) has such an internal diameter as to form a clearance to become an insulating air layer (9) between itself and the outer circumference of the center tube (4). The support tube (8) includes a plurality of supporting portions (8c) formed on the axially upstream side and contacting the inner circumference of the outer tube (5) radially, a plurality of groove portions (7a) formed axially between the supporting portions (8c), and a cylindrical portion (8b) formed on the axially downstream side and having an external diameter equal to or smaller than that of the groove portions (7a). The space, which is formed by the outer tube (5) and the groove portions (7a), and the space, which is formed by the outer tube (5) and the cylindrical portion (8b), are used as the gas fuel passages, in which the gas fuel flows.