To increase the solubility of lyophilized sericin, we added three types of lyoprotectant: sucrose, trehalose and dextran. The addition of lyoprotectant increased the solubility of lyophilized sericin especially when 1.0% of sucrose, 1.0% and 1.5% trehalose are added. The secondary structure of lyophilized sericin showed that the content of ${eta}$-sheet or aggregated structure reduced in the presence of lyoprotectant. The morphology of lyophilized was also affected by the addition of lyoprotectant. Whereas flake structure was obtained in the case of pure sericin, a scattered and relatively small flake structure was formed in the presence of lyoprotectant. These finding shows that the presence of lyoprotectant prevents aggregation of sericin molecules and increases the solubility of lyophilized sericin.