A method for preparing a sericin hydrogel, the method including: 1) weighing a cocoon of a fibroin-deficient mutant silkworm, Bombyx mori, extracting the cocoon by an aqueous solution of LiBr or LiCl, dialyzing an extracted solution to yield a sericin solution having a concentration of a non-degraded sericin of between 0.1 and 4 wt. %; and 2) concentrating the sericin solution to a concentration of between 1.5 and 10 wt. %, adding a crosslinking agent to the concentrated sericin solution at a ratio of between 2 and 500 μL of the crosslinking agent per each milliliter of the sericin solution, fully blending the crosslinking agent with the concentrated sericin solution, and keeping a resulting mixture at the temperature of between 4 and 45° C. for between 5 s and 36 hrs to yield a hydrogel.