A method is provided for operating a blast furnace by blowing a solid reducing material, a flammable gaseous reducing material and a combustible gas into a blast furnace from tuyeres through a lance into a blast furnace, wherein a parallel type lance prepared by bundling three independent blowing tubes in parallel and integrally housing them into an outer tube is used, and either one or both of the gaseous reducing material and the combustible gas and the solid reducing material are simultaneously blown through the respective blowing tubes, while the blowing tube for the solid reducing material and the blowing tube for the gaseous reducing material are positioned above the blowing tube for the combustible gas in the blowing through the parallel type lance as well as a lance structure thereof.