PROBLEM TO BE SOLVED: To solve a problem that a material in which a silk fibroin is utilized has stiffness and lacks flexibility.SOLUTION: The composition comprises fibroin and a polymeric material different from fibroin, and in which the polymeric material has a decomposition period in the rat abdominal cavity of 4 days or more and 360 days or less and has a Young's modulus of 0.4 MPa or more and 4,000 MPa or less. The polymeric material may comprise at least one of polyethylene carbonate and polydioxanone. The fibroin and the polymeric material may form a phase separation structure having a first phase made of fibroin and a second phase made of polymeric material in the composition.SELECTED DRAWING: Figure 34
