Airborne radionuclides from the accident of Fukushima Dai-ichi Nuclear Power Plant (FDNPP) in 2011 were measured at the RIKEN Wako Institute, Japan, about 220 km to the southwest of FDNPP, from March 15, 2011 to March 16, 2012. Radioactivity concentrations of 140 Ba, 137 Cs, 136g Cs, 134g Cs, 133g I, 132 Te, 131 I, 129m Te, 110m Ag, 99 Mo, and 95g Nb (m: metastable state; g: ground state) were determined by γ-ray spectrometry with a germanium detector. The time variations of the radioactivity concentrations and their ratios in Wako are discussed by referring to those of the ambient effective dose rate as well as the amount of rainfall. The pronounced peaks of the radioactivity concentrations were observed on March 15, 20-21, and 29-31, 2011. The highest concentrations for typical radionuclides in unit Bq m-3 were 8.8 ± 0.2 for 137 Cs, 1.2 ± 0.2 for 136g Cs, 8.5 ± 0.2 for 134g Cs, 4.7 ± 0.3 for 133g I, 58 ± 2 for 132 Te, 8.0 ± 1.2 for 129m Te, and 35 ± 1 for 131 I in the sample collected in the period of March 15, 2011, 11:15-11:45 JST (Japan Standard Time). The 134g Cs/ 137 Cs radioactivity ratio was determined to be 1.0 ± 0.1 for March 11, 2011, and this value was consistent with other observations related to the FDNPP accident. The environmental radioactive contamination in Wako occurred mainly on March 21, 2011, due to the first rainfall after the accident. Keywords: Fukushima Dai-ichi nuclear power plant accident, airborne radionuclide, 131 I, 137 Cs, 134g Cs † Japan Standard Time (JST) is consistently used in this paper; JST = UTC (Universal Time, Coordinated) + 9 h.