The morphological characters of a dwarf common buckwheat line, G410, its dwarf stability under different growth conditions and mode of inheritance were investigated. Dwarfism of G410 is the result of reduction in length in the first four internodes, especiaHy in the second- and the third internodes from the soil. The other internodes and organs were not reduced in size. Therefore, G410 shows the brachysm type dwarfism, which is valuable for both root lodging- and stem lodging resistance. Although buckwheat is sensitive to growth conditions and its stem elongates longer under long day or high nitrogen conditions, the morphological characters of G410 were unaffected by seeding date, planting density and nitrogen conditions. F₁ plants of G410 crossed with a normal variety, Botan-soba, appeared intermediate and segregation ratios in the F₂ and BC₁F₁ generations fitted a single gene model. Therefore, dwarfism of G410 was controlled by a single incompletely dominant gene, probably which is a new gene because all dwarfing genes reported previously are recessive. Under this inheritance system it is possible to distinguish genotypes by phenotype and to select dwarf homozygotes. These results indicate that G410 is a material worth further investigation for breeding lodging resistance in common buckwheat.