Abstract: An air-conditioning duct for vehicles with one duct mutually connected and fixed to the other duct is provided. One duct is formed by incorporating a first unit duct with a flange formed around an opening periphery thereof and a second unit duct with a flange formed around an opening periphery thereof in parallel. The other duct is formed by incorporating a third unit duct with a flange formed around an opening periphery thereof and a fourth unit duct with a flange formed around an opening periphery thereof in parallel. The flange formed on the boundary side of the second unit duct are fixed with one over another, and the flange formed on the boundary side of the third unit duct and the flange formed on the boundary side of the fourth unit duct are fixed with one over another.