We aimed to estimate the amount of radiocesium re-dispersed by sugi (Cryptomeria japonica var. japonica) pollen release accurately based on measurements of sugi male flowers before pollen release. We measured the biomass and cesium-137 (¹³⁷Cs) concentrations in male flowers and sugi pollen in November (shortly after pollen maturity), and in the following February (shortly before pollen release), in forests impacted by the 2011 Fukushima Daiichi Nuclear Power Station accident. Pollen accounted for ca. 1/3 of male flower biomass and the ¹³⁷Cs concentrations were not significantly different between male flowers and pollen in November in the Koriyama sugi forest. The regression relationship between male flower and pollen 137Cs concentrations was used to calculate pollen ¹³⁷Cs concentrations for every November–December period in the years 2011–2015 at 21 localities in Fukushima Prefecture. The sugi pollen ¹³⁷Cs concentration declined year on year. The concentration in the spring of 2016 was ca. 8% of the concentration in spring 2012. The calculated ¹³⁷Cs T_ag (aggregated transfer factor) for the transmission of ¹³⁷Cs from the environment to pollen was 0.0203 m² dry kg^–1 in February 2012 and 0.00168 m² dry kg^–1 in February 2016, based on data available in the MEXT ¹³⁷Cs deposition quantity distribution map.