The invention relates to food and pharmaceutical industry, in particular, to comprehensive processing inulin-containing vegetable raw materials. The technical result attained is production of a powder having a high content of purified inulin already at the first stage of processing an inulin-containing raw material by a so called dry method. The essence of the method for processing inulin-containing raw materials to produce food-grade inulin powder consists in that the chopped raw material is dried by mopping to remove surface moisture and subjected to infrared drying to a moisture content of 10-12%, with subsequent holding for 4-6 hours. The dried raw material is ground to a particle size of less than 100 μm, and the resulting powder is re-dried to a moisture content of 5-10%. The ground raw material is divided into fractions according to the particle size : less than 15 μm - the first one, 15-25 μm - the second one and 25-100 μm - the third one. The second fraction is dried to a moisture content of 5-6% and subjected to re-grinding, followed by separating the particles smaller than 15 µm that are combined with the first fraction and used as food-grade inulin. The residues of the second fraction are combined with the third fraction and used for producing ultra-pure inulin by the diffusion method.