[Problem] To provide a method for efficiently incorporating a drug that is to function in muscle tissue, but when administered to an organism is itself not adequately incorporated into muscle tissue, into muscle tissue, particularly into muscle tissue constituted of skeletal muscle or heart muscle. [Solution] A complex of a drug and an anti-human transferrin receptor antibody, wherein the drug is a drug having a physiological activity that is to exhibit functionality in muscle tissue, for example, a lysosomal enzyme such as acidic a-glucosidase or a-galactosidase A.
