The present invention provides a lactoferrin fusion protein having high clinical utility and a production method therefor. The present invention further provides: a lactoferrin fusion protein that retains the biological activity of native lactoferrin while having a significantly extended in vivo life span, and that has more clinical utility than native lactoferrin and recombinant lactoferrin; and a production method therefor. With this fusion protein or a variant thereof, the ability of lactoferrin to bind iron is retained, and therefore at least the important biological activity of lactoferrin that is based on the iron-binding ability is retained. Additionally, this fusion protein or variant thereof has bioavailability and resistance to protease, and thus can exhibit biological activity in vivo over a long period. Furthermore, this fusion protein is not easily broken down by pepsin in the stomach.