The amylopectin long-chain rice “Konayukinomai” (MAI) is high in resistant starch (RS). In this study, we confirmed that fine rice flour for bread making could be obtained using MAI, and compared the results to the high-amylose cultivar “Koshinokaori” (KOR) and the conventional cultivar “Koshihikari” (HKR). MAI bread contained larger amounts of RS and slowly digestible starch (SDS) than that of HKR or KOR, and the RS content of MAI was easily changed by retrogradation and re-gelatinization of the starch. In a clinical trial with healthy volunteers, MAI and KOR breads could prevent abrupt increases in blood glucose and showed low glycemic index (GI) values compared to HKR bread. From the above results, we propose that SDS and RS prevent increases in blood glucose, and consider MAI to be a promising rice cultivar as a nutraceutical food material for the prevention of lifestyle-related diseases.