||Silkworm silk has been known for various usages including sutures and textiles. However, during the degumming process, a mass amount of silk sericin is discarded. Since silk sericin has a variety of advantageous properties, such as biocompatibility, hydrophilicity, and excellent moisture retention, there have been continuous studies on reusing silk sericin in various fields. Under pH condition below its isoelectric point, silk sericin can form hydrogel, which is induced by hydrophobic, electrostatic interactions. In this study, we fabricated sericin hydrogels via gradual acidification by glucono-delta-lactone (GDL). GDL slowly hydrolyzes into gluconic acid, lowers the pH and finally fabricates sericin hydrogel. For comparison, we prepared sericin hydrogels via instant acidification by 1M HCl. The structural properties of both hydrogels were investigated by FE-SEM and FT-IR. Furthermore, several measurements, including zeta-potential, were performed to identify the gelation process.