The high variability of the soil-to-plant transfer factor of radiocaesium requires a detailed analysis of the radiocaesium interception potential (RIP), one of the specific factors determining the radiocaesium transfer. The RIP values ranged a factor of 50 among 51 representative surface soils collected from the Fukushima accident affected area. Correlation analysis revealed that the RIP was negatively and most strongly correlated to the soil organic matter content, suggesting that soil organic matter can mask highly selective sorption sites of radiocaesium. The slope of the correlation between the RIP and the clay content showed that the RIP per unit clay content was 4.8 mmol/g clay, about threefold lower than that for clays for European soils, indicating more amorphous minerals and less micaceous minerals in the clay fraction of Japanese soils. Multiple regression analysis with soil organic matter and cation exchange capacity explained the soil RIP (R2 = 0.64), allowing us to map the soil RIP based on existing soil map information.