Nowadays, some sushi restaurants utilize long-term aged fish and shellfish sashimi as a foodstuff, as it is believed to have a unique texture and rich umami taste. However, changes in the quality of fish and shellfish sashimi during long-term aging remain unclear. In this study, taste components and texture of long-term aged fish and shellfish sashimi were evaluated for comparison with those of conventional sashimi. Greater amberjack Seriola dumerili, oval squid Sepioteuthis lessoniana, marlin Kajikia audax, and white trevally Pseudocaranx dentex were used as sashimi materials. These samples were aged at 1℃ for 13 to 31 days, respectively. All the sashimi samples before and after aging were obtained from sushi restaurants. Inosine 5′ monophosphate (IMP) content, firmness, moisture content, and expressible drip decreased in the long-term aged sashimi samples, and conversely their free amino acid contents increased. K values of these samples were 46.7-76.5%, and protein degradation was observed in SDS-PAGE. These results indicate that long-term aged fish and shellfish sashimi have different taste components and texture from those of the conventional sashimi that emphasizes freshness, and thus can be utilized as a new aquatic food product.