In order to investigate hydantoinase-producing strain of the genus Streptomyces, 523 strains of Streptomycee sp. isolated from soils were cultivated in various media and conversion activity of the enzyme was measured to DL-5-phenylhydantoin. A number of strains producing hydantoinase were detected and among them, the strain of Streptomyces sp. Y-183 was selected as a most powerful strain to producing the enzyme. The optimal culture conditions for the production of hydantoinase of the strain were studied, and it was found that almost all hydantoinase activity was produced in the cell fraction. The maximum activity of the enzyme, 17.8 unitstg of dried cells weight, was obtained when the strain was cultured at $30^{circ}C$ for 72 hr in a medium containing 1.0% of glycerol. 0.5% of yeast extract. 0.5% of soytone, 0.5% of beef extract, 0.6% of KCI, 0.002% of $K_2HP0_4, 0.25% ;of ;CaC0_3, ;0.0002% ; of ; ZnSO_4, ; 0.0002%; of; FeS0_4$, and 0.4% of uracil as an inducer, and the pH of culture broth was adjusted ranging from 7.0 to 7.5.