We measured the effects of rain attenuation on 120-GHz band wireless link during the heavy rainy period (from July to September, 2008) and annual period (from March to December, 2008). The heavy rainy period data are used as a basis for the wireless link design, and the annual data are used to calculate the reliability of the wireless link. The 120-GHz band wireless link with V polarization was operated on a 400-m-long path from March to December 2008 in Atsugi, Japan. The rain rate distribution for Atsugi is in good agreement with the conditional M distributions. As for rain attenuation, the annual data coincide with the ITU and Laws and Parsons models. Cumulative distributions of attenuation and bit-error-rate deterioration due to rain were obtained.