Carotenoids and their fatty acid esters in the carapace of the spiny lobster Panulirus japonicus were investigated. Fatty acid esters of astaxanthin, adonixanthin, and pectenolone were characterized by (1)H-NMR and FAB-MS. The acylated position of adonixanthin and pectenolone monoesters was determined to be a hydroxy group at C-3' by (1)H-NMR. The fatty acids esterified with these carotenoids were identified as C22:6, C20:4, C20:5, C18:0, C18:1, C17:0, C16:0, C16:1, C14:0, and C12:0 from FAB-MS spectral data. Furthermore, 2,3-didehydrocanthaxanthin (4) was first identified as a natural product.