There is provided a heat-insulating and noise reducing duct constituted by reinforcing core 1, a thick felt layer 2, a foamed resin strip layer 3 and a resin-coating layer 4. The reinforcing core 1 is made of hard polyolefin resin material and wound spirally at predetermined intervals. The thick felt layer 2 is wound spirally on an outer circumferential surface of the reinforcing core so that adjacent side edge portions of the felt layer 2 are lapped over or brought into contact with each other, while the shape of the felt layer is retained by the reinforcing core 1. The foamed resin strip layer 3 made of polyolefin resin material and wound spirally on an outer circumferential surface of the felt layer 2 so that adjacent side edge portions of the foamed resin strip layer 3 are in abutment against or in tight contact with each other. The resin-coating layer 4 provided to cover an outer circumferential surface of the foamed resin strip layer 3. Accordingly, it is possible to provide a sound-absorbing and heat-insulating duct which is simple, not complicated, in structure, which can achieve both sound-absorbing and heat-insulating functions, which is suitable for use as an air-blow duct, and which is suitable for continuous production so that the duct can be mass-produced inexpensively without requiring any new equipment.