Abstract: For further understanding the impacts of the accident of Japan's Fukushima-Daii-Chi Nuclear Power Plant on the radioactivity levels of marine organisms and the public radiation dose. The radioactivities of gross alpha and gross beta from the organs and tissues of Ommastrephes bartramii collected from the northwest Pacific Ocean after the accident were measured and analyzed. The results showed that the activity concentrations of gross alpha and gross beta in the organs, particularly the liver, of the O. bartramii were significantly higher than those of other soft tissues. The activity concentration of gross beta in the O. bartramii was significantly higher than that of gross alpha activity. In addition, the radiation dose of the O. bartramii was evaluated during three time periods in the waters adjacent to Japan and in the western Pacific Ocean by using the nuclide activity concentration levels in the marine environment published internationally. The results show that according to the open data, the impacts were serious and would last for a long time in the adjacent waters of Japan while it was limited and would last for a shorter time in the far western Pacific Ocean.