The nutritive value of Capsosiphon fulvescens (C. Agardh) Setchell et Gardner, a new developing species for cultivation of marine macroalgae in Korea, was assessed by comparison with common edible green seaweed Ulva prolifera (Oeder) J. Agardh collected from Korea and Japan, based on analysis of its chemical composition. The contents of protein and of total, essential, and free amino acids of C. fulvescens were significantly higher than those of U. prolifera, whereas those of lipid, carbohydrate, and total dietary fibres were significantly lower. There were no significant differences in the moisture content between Capsosiphon and Ulva species. The main minerals of Capsosiphon and Ulva are Na, Mg, K, Ca, and Al, making up approximately 97-99 % of the total minerals. The contents of Na and V of Capsosiphon were significantly greater than those of Ulva, while those of Mn and Sr were significantly lower in Capsosiphon. The contents of retinal (27.8 μg g −1 dry wt) and ascorbic acid (0.28 mg g −1 dry wt) of Capsosiphon were significantly higher than those of Ulva, but the contents of cobalamin were lower. These results suggest that C. fulvescens has greater potential to be used as human food and as an ingredient in formulated food.