The coconut crab (Birgus Latro), the largest terrestrial arthropod in the world, contains carotenoid pigments mainly in the shell, although no previous studies have identified them. We isolated the pigments in this study, by EtOAc extraction, silica gel column chromatography, and GPC column chromatography.We identified them as astaxanthin [optical isomeric ratio: (3R, 3’R), 9%; (3R, 3’S; meso), 41%; (3S, 3’S),50%] and diacyl astaxanthins [fatty acid ratio: stearic acid (18:0), 46%; palmitic acid (16:0), 26%; and oleic acid (18:1n-9), 18%] by ¹H-NMR, LRESI-MS, chiral phase HPLC and GC analyses. This is the first detailed analysis of the carotenoids contained in coconut crab. We also examined the antioxidative activity of isolated astaxanthin and diacyl astaxanthins in the singlet oxygen suppression model. These compounds showed equal antioxidative activities with an IC₅₀ value of 4 μM.