The purpose of this paper is to explore the possible applicability of alginate beads as an oral controlled release system of polymeric drugs. Cellulase was used as a model polymeric drug. The release of cellulase from alginate beads was moderately affected by the ratio of cellulase to sodium alginate and strongly affected by $CaCl_2$ concentration. However, the release was not particularly affected by the other factors such as sodium alginate concentration and curing time. The drug was not released from alginate beads at pH 1.2, but was released continuously up to 8 hr at pH 6.8. At pH 6.8, the beads were swollen highly up to 3 hr, thereafter, were eroded into the bulk solution up to 6 hr, completely. Drug release from the beads can be caused due to diffusion and erosion of the matrix. Activity of cellulase was reduced when alginate beads containing cellulase were stored in simulated gastric juice. Further investigation would be necessary to improve the acid resistance of the beads. Since the release of cellulase as a model polymeric drug could be controlled by the regulation of the preparation conditions of alginate beads, the alginate beads may be used for a potential oral controlled release system of such polymeric drugs as polypeptide drugs.