This paper deals with investigation on the various effects of phosphodiesterase production of Streptomyces sp. and several properties of the enzyme. The results were as follows. 1) As a carbon source, sucrose was most effective PDase production when it was added. to the basal medium at 3％ concentration. 2) These enzymes were remarkably activated by $Ca^{2+}$, Co$^{2+}$ and Mn$^{2+}$ but inhibited by Cu$^{2+}$. It was observed that concentration of metal ions, 0.1％ of $Ca^{2+}$, 0.01％ of Co$^{2+}$ and 0.04％ of Mn$^{2+}$ were effective on the production of phosphodiesterase and phosphomonoesterase. 3) In case of the effect of aeration volume, 25 ml was very effective, that is, the more sufficient aeration, the better enzyme activity. Enzyme activity was to be found effective at 3％ of inoculation volume, and comparatively more effective at 2％, 4％ of inoculation volume. 4) Initial pH was 8. The enzyme activity reached to the maximum at 48 hours of cultivation time. 5) The optimum pH of phosphodiesterase was about 8 and that of phosphomonoesterase was about 9. The optimum temperature of phosphodiesterase and phosphomonoesterase was 6$0^{circ}C$ and 5$0^{circ}C$ respectively. respectively.