The effectiveness of the resting cells of a photosynthetic bacterium, Rhodocyclus gelatinosus KUP-74, was investigated on the production of extracellular δ-aminolevulinate (ALA). The ALA generating system with 1.05 ㎎ cells per milliliter required 6 hr-incubation to obtain maximal yield of extracellular ALA. Under this condition ALA inducers, i.e., levulinate or L-glutamate showed relatively low effects to increase extracellular ALA production. Instead, the volume of the system and proper cell density appeared to be important factors for effective production of the ALA. The life-span of the resting cells was remarkably extended to maintain stable production of the ALA by immobilization of cells.