The isolation, purification and characterization of a carotenoprotein from the carapace of Pnaeus orientalis were investigated. The carotenoprotein was purple with broad λmax between 480, 409, 318 and 280 nm. Apparent structures were estimated by using X-ray diffractometry and scanning electron microscope, respectively. The molecular weight of the carotenoprotein complex had been determined by GPC and PAGE. The heavier complex, designated the $alpha$-form (M.W = 170 KDa), was dissociated to a major subunit, $eta$-form (M.W = 42 KDa). SDS-PAGE of $alpha$-form showed apparently oligomeric pattern, and also $eta$-form gave two polypeptides corresponding to 22 KDa and 19 KDa, respectively. The amino acid of the two proteins $({alpha}-and;{eta})$-form, lipid and free fatty acid compositions were described. The prosthetic groups of the carotenoprotein were confirmed by TLC, IR, <TEX>$^1H$<TEX>-NMR, MS and various organic reactions as astaxanthin, astaxanthin monoester and astaxnathin diester.