The shattering resistance in five mutant lines was found to be controlled by a single recessive gene. The analysis was carried out using the F1, F2 and F3 populations that were derived from the reciprocal crosses between five mutant lines and the oritginal variety, Nan-jing 11. The allelism test using the twenty F2 populations bred by the reciprocal crosses among five mutant lines, indicated that 1) the three mutant genes of SR-4, Hokuriku143 (SR-5) and SR-6 were located at the same locus, 2) the genes of SR-1, SR-2 and these three lines were located at different loci. The classification of the five mutant lines by their mutant loci coincided with the shattering degree and the formation of abscission layer. The SR-1 group showed a high shattering resistance without abscission layer. SR-2 group was moderately resistant to shattering with the presence of slightly decayed cells in the region between the rudimentary glumes and sterile glumes in a spikelet. The last group consisting of SR-4, SR-5(Hokuriku143) and SR-6 was resistant to shattering with cells displaying a higher level of decay than in the case of SR-2. These five mutant genes were classified into three groups in relation to the formation of abscission layer. It was also assumed that the original shattering gene(s) in Nan-jing 11 that was/were partial dominant was/were involved in the formation of the abscission layer or shattering degree, since the shattering degree and the formation of the abscission layer in F1 plants were intermediate between those of the parents. These results indicate that Nan-jing 11 harbours three partial dominant genes related to the formation of the abscission layer and/or shattering habit.