Disclosed are novel anti transferrin receptor antibody that can pass through the blood-brain barrier, a fusion protein comprising a protein necessary to be brought into function in the central nervous system and the antibody, and method of their production. The fusion protein comprises amino acid sequences of an anti-human transferrin receptor antibody that recognizes an amino acid sequence selected from the group consisting of SEQ ID NOs:1, 2, and 3, and of other protein that is bound thereto on the C- terminal side.