A main fuel injector of a fuel injection device includes: a main outer air passage including an inlet that is open outward in a radial direction, the main outer air passage taking in compressed air through the inlet; a main inner air passage including an inlet that is open inward in the radial direction, the main inner air passage taking in the compressed air through the inlet; a merged air passage, in which the compressed air taken in by the main outer air passage and the compressed air taken in by the main inner air passage merge together; and a main fuel injection port configured to inject a fuel into the compressed air taken in by the main outer air passage or into the compressed air taken in by the main inner air passage.