The present invention aims to provide a lactoferrin fusion protein, which is configured to retain the biological activities of natural lactoferrin, to have a significantly prolonged in vivo lifetime, and to be more clinically useful than natural and gene recombinant lactoferrin, as well as a method for preparation thereof, etc. The present invention provides a fusion protein formed with a protein or peptide comprising an FcRn-binding region and lactoferrin or a biologically active fragment or peptide of lactoferrin, which is represented by: (LF-s-Y)n or(Y-s-LF)n [wherein LF represents lactoferrin or a biologically active fragment or peptide of lactoferrin, Y represents the protein or peptide comprising an FcRn-binding region, s represents any amino acid sequence of 0 to 10 residues, and n represents an integer of 1 to 10], or a variant thereof.