Bunker-A oil-degrading microorganisms were isolated from a marine environment using an enrichment culture technique. The isolated strain EL-081K was identified as the genus Acinetobacter based on the results of morphological, culture, and biochemical tests. The optimal temperature and initial pH for bunker-A oil degradation were $25^{circ}C$ and 7.0, respectively, including aeration. The optimal medium composition for the degradation of bunker-A oil by Acinetobacter sp. EL_O81K was 10 ml/l bunker-A oil as the carbon source and 0.1% (NH$_4$)$_2$SO$_4$as the nitrogen source. Under the above conditions, the biodegradability of bunker-A oil was 38% after 96 hours of incubation. The addition of detergent did not increase the bunker-A oil degradation.