The purpose of this study was to isolate an agar-degrading marine bacterium and characterize its agarase. Bacterium BK-1, from Gwanganri Beach at Busan, Korea, was isolated on Marine 2216 agar medium and identified as Agarivorans sp. BK-1 by 16S rRNA gene sequencing. The extracellular agarase, characterized after dialysis of culture broth, showed maximum activity at pH 6.0 and $50^{\circ}C$ in 20 mM Tris-HCl buffer. Relative activities at 20, 30, 40, 50, 60, and $70^{\circ}C$ were 67, 93, 97, 100, 58, and 52%, respectively. Relative activities at pH 5, 6, 7, and 8 were 59, 100, 95, and 91%, respectively. More than 90% of the activity remained after a 2 hr exposure to 20, 30, or $40^{\circ}C$; about 60% of the activity remained after a 2 hr exposure to $50^{\circ}C$. Almost all activity was lost after exposure to 60 or $70^{\circ}C$ for 30 min. Zymography revealed three agarases with molecular weights of 110, 90, and 55 kDa. Agarose was degraded to neoagarobiose (46.8%), neoagarotetraose (39.7%), and neoagarohexaose (13.5%), confirming the agarase of Agarivorans sp. BK-1 as a ${\beta}$-agarase. The neoagarooligosaccharides generated by this agarase could be used for moisturizing, bacterial growth inhibition, skin whitening, food treatments, cosmetics, and delaying starch degradation.