The object is to provide a method for removing a sialic acid that can be carried out simply at a low cost and a method for producing asialoerythropoietin using the same. The method for removing a sialic acid according to the present invention includes an acidifying and heating process of acidifying and heating a solution containing erythropoietin so as to remove a sialic acid bonded to an erythropoietin molecule. Further, the method for producing asialoerythropoietin according to the present invention includes a sialic acid removing process of removing a sialic acid bonded to an erythropoietin molecule by the method for removing a sialic acid according to the present invention.