Car-borne surveys were carried out on eight islands of the Izu Islands located 339-570 km southwest of the Fukushima Daiichi Nuclear Power Plant. The mean dose rates measured in 2015, 2016 or 2017 on each island were from 12 to 47 nGy h-1, meaning that the contribution ratios of artificial radionuclides were 5-31%. Based on the environmental half-life for long half-life radionuclides (134Cs + 137Cs) measured on Izu-Oshima (3.1 y), the mean dose rates in March 2011 were estimated to be 15-53 nGy h-1 and the contribution ratios of artificial radionuclides were 11-55%. The estimated annual external effective doses were 0.06-0.21 mSv which were 13-44% of the worldwide average (0.48 mSv).