The rice stink bug, Niphe elongata (Dallas) (Hemiptera: Pentatomidae), is a re-emerging pest that has seriously infested rice over a wide area of western and central Japan since the 2000s. This study developed a novel method for rearing this insect using mixed grains of brown rice, wheat, and foxtail millet supplemented with solution of vitamin C. While the body size of emerged adults reared using this method was smaller than that of field-collected ones, 39.2% of individuals developed from first instar nymph to adult at 28℃ under a 16:8 h L:D photoperiod, had an average developmental period of 25.4 days. We maintained a strain of the insect for eight generations over 14 months without the addition of field-collected individuals. The diet was easy to prepare throughout the year. This convenient technique for rearing N. elongata will promote field and laboratory studies of the biology of this pest.