Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), found in seafood, are essential fatty acids and therefore must be obtained from the diet. Traditionally, Japanese cuisine is centered around fish as the main ingredient. However, in recent years, a social problem has arisen wherein members of both the younger and the older generations eat progressively less fish. Canned fish is an easy-to-prepare fish food, but because vegetable oil is added to the can, it is important to investigate whether canned fish is an appropriate source of n-3 fatty acids. In this study, we divided canned tuna products by fish and oil type and analyzed fatty acid content in the fish part and the oil part to simulate an ordinary serving. From the 300 top-selling tuna can products, we selected 3 different types of tuna (bluefin tuna, yellowfin tuna, and albacore tuna) packed in soybean oil, as well as albacore tuna packed in 4 types of oil (soy, cottonseed, olive, and safflower oils). Furthermore, cans of the 3 types of tuna packed in water were used as controls. The findings revealed that tuna in water contained a suitable amount of n-6/n-3, but a low amount of EPA+DHA. Among tunas in oil, albacore tuna had the higher level of EPA+DHA, and added olive oil contained the lower amount of n-6/n-3. Our finding showed that n-3 fatty acid content in tuna varies widely depending on the added oil, and that the EPA+DHA level of canned tuna is low. Therefore, it is not so appropriate the canned tuna as a source of omega-3 fatty acids.