[Problem] To provide a method for producing a fusion protein obtained by fusing an antibody with a lysosomal enzyme. [Solution] A method for producing a fusion protein obtained by fusing an antibody with a human lysosomal enzyme, wherein the production method includes (a) a step for culturing mammalian cells that produce the fusion protein in serum-free medium to cause the fusion protein to be secreted in the culture broth, (b) a step for recovering the culture supernatant by removing the mammalian cells from the culture broth, and (c) a step for purifying the fusion protein from the culture supernatant using column chromatography in which a material to which is bonded a substance having an affinity for the fusion protein is used as the stationary phase, column chromatography in which a material having an affinity for phosphate groups is used as the stationary phase, and size-exclusion column chromatography.
