Total 176 alginate-degrading bacterial strains were isolated from marine moluscus, marine echonodermata, seaweed, and soils. Among the isolates, five strains (No. 28, 51, 79, 135, and 145) had higher level of alginate-degrading activity. The isolate No. 28, 51, 79, and 135 were identified as the genus Enterobacter and the strain No. 145 as the genus Vibrio. We used these strains to examine the optimal conditions for the production of alginate-degrading activity.