There are provided a Kringle domain structure, comprising: inducing artificial mutations at amino acid residues except for conserved amino acid residues that are important to maintain the structural scaffold of a Kringle domain; and protein scaffold variants, based on the Kringle domain structure, which modulate the biological activities of a variety of target molecules derived from the protein scaffold library by specifically binding to the target molecules. Also, there is provided a method for constructing homo-/hetero-oligomers which allow multi-specificity binding to multiple targets by the tandem assembly monomeric Kringle domain variants using a linker. Additionally, there is provided a method for preparing multispecific monomers and multivalent monomers by grafting target-binding loops of a Kringle domain variant into non-binding loops of another Kringle domain variant with the same or different target binding specificity. Furthermore, a protein scaffold variant based on the Kringle domain structure that specifically binds to target molecules, DNA encoding the protein scaffold variant, or a method and composition for prevention, detection, diagnosis, treatment or relieving diseases or disorders, particularly cancers and other immune-related diseases, comprising: administering an effective amount of the related molecule to animals, preferably human.