In　this　study,　two　antioxidative　substances,　a　homogeneous　polysaccharide　[abalone　shell　polysaccharide　(ASP-1),　corresponding　to　the　first　peak　by　size　exclusion　chromatography]　and　a　non-polysaccharide　compound　[abalone　shell　compound　(ACS-2),　corresponding　to　the　second　peak　by　size　exclusion　chromatography],　were　extracted　from　the　abalone　(Haliotis　discus　hannai　Ino)　shell.　We　primarily　focused　on　the　investigation　of　ASP-1.　As　a　heteropolysaccharide,　ASP-1　is　comprised　of　9.3%　uronic　acid　and　86.4%　saccharide,　the　latter　including　mannose,　ribose,　rhamnose,　glucose,　galactose,　arabinose,　and　two　unknown　monosaccharides,　NO1　and　NO2,　with　a　mass　ratio　of　9.5:10.1:2.2:18.2:21.8:5.5:16.5:16.2.　The　antioxidant　activity　assays　indicated　that　5.0　mg/mL　ASP-1　has　significant　scavenging　effects　on　superoxide　radicals　(86.2%)　compared　to　the　positive　control　of　ascorbic　acid　(95.6%).