Three individuals in progeny from each of 39 crosses and their parents in Japanese persimmon (Diospyros kaki Thunb.) were evaluated for fruit ripening time. Analysis of variance for the progeny, which estimated between- and within-cross variance, and the regression of the mean value in a full-sib family on the mid-parental value (MP) revealed that the genetic differences among crosses could be explained solely by MP. Genotypic values of individuals in progeny from a cross were assumed to be normally distributed around the regression line with within-cross genetic variance. Based on the parental mean performance of 3.5 fruit on a single tree for three years, the coefficient of regression of mean values in a full-sib family on MP was 0.99 ± 0.10, and the proportion of individuals in progeny having genotypic values ripening earlier than early October was estimated as 52%, 24%, and 7% for three sets of mid-parents differing in their ripening time, i.e., early, middle, and late October, respectively. On the basis of the parental mean performance in 10 fruit on a single tree without yearly repetition, the regression coefficient was estimated as 0.91 and the proportion was estimated as 44%, 20%, and 6% for the three sets of mid-parents, respectively.