the present invention relates to a fusion protein comprising small heat shock protein , a cage protein formed thereby , and novel use thereof , more particularly , a fusion protein comprising a small heat shock protein , a recognition site of a protease , and a histidine polymer , wherein the recognition site and the histidine polymer are sequentially linked to a carboxyl terminal of the small heat shock protein , a cage protein formed thereby , and novel use thereof . the fusion protein of the present invention , and a cage protein formed by the self - assembly properties of the fusion protein are not cytotoxic , and emits a fluorescence signal of about 20 to about 50 times higher comparing to a single peptide for the conventional molecular imaging , per unit protein . additionally , cell permeability is very excellent , thereby to be effectively used as a biosensor or a bioactive material carrier .