An anti-icing system according to the present invention includes: a piccolo tube that includes a flow path through which heated gas flows in the longitudinal direction from a rear end to a front end, and a plurality of ejection holes provided along the longitudinal direction to make the flow path communicate with an outside; and an engine serving as a supply source that supplies the heated gas toward the piccolo tube. The piccolo tube is decreased in an area of the flow path in a stepwise manner or in a continuous manner in the longitudinal direction, and has a continuous side surface provided with the ejection holes.