This study was conducted to determine the effect of food combinations of leguminous seeds on the nymphal development and adult fecundity of Riptortus clavatus Thunberg. Nymphal duration ranged from 20 to 28 days depending on food combinations with the shortest on the seed of soybean (Glycine max Linnaeus), soybean + kidney bean (Phaseolus vulgaris Linnaeus) and soybean ＋ peanut (Archis hypogaea Linnaeus) and the longest on the seed of kidney bean. Instar duration was longer with increasing instar from 2.4 to 2.5 days in the 1st instar to 5.3 to 7.3 days in the 5th instar Accordingly, instar duration was significantly different on food combinations exception of 1 st instar Percent emergence varied from 3.5％ on peanut to 65.0％ on the seed of soybean ＋ peanut. Nymphal mortality was the highest in the 1 st instar regardless of food combinations. Adult longevity was in range of 5.5 days to 11.2 days which was the shortest on the seed of kidney bean+peanut and the longest on soybean ＋ peanut and was about 8.0 days on the other food combinations. Total number of eggs laid by female was most on soybean+peanut and was least on kidney bean ＋ peanut. Accordingly, it can be recommended that food combination of the seed of soybean ＋ peanut was the best and then was soybean only while other food communications of leguminous seeds was hard to use for mass rearing of R. clavatus.