The formation of silk fibroin (SF) hydrogel can be adjusted by changing physical conditions such as concentration of SF aqueous solution, temperature, pH and salts. In this study, tyrosinase (Tyr), which is an enzyme catalyzing the oxidation of phenols such as tyrosine, was used to decrease the gelation time of SF aqueous solution under a fixed conditions. Tyr oxidizes a broad range of phenols into very reactive o-quinones, and consequently quinones undergo non-enzymatic reactions with various nucleophiles. So it is expected that the gelation time of SF aqueous solution could be decreased by polyphenol compound such as caffeic acid and chlorogenic acid. The color of SF aqueous solutions containing Tyr was changed into deeper yellow with Tyr concentration, and also the gelation time of SF aqueous solution slightly decreased. However, the effect of Tyr concentration on gelation time of SF aqueous solution was not significant due to the locational hindrance of tyrosyl residues in SF. Absorbance at 550 nm also showed conformational transition (random coil to $eta$-sheet conformation) of SF structure. When polyphenol compounds were added into SF/Tyr aqueous solution, the gelation time slightly decreased. However, the phase separation occurred when polyphenol compounds more than 5 mM were added. The results obtained in this study indicate that enzyme and additives have a potential to regulate the gelation behavior of SF aqueous solution, to some extent.