Grain yield, one of the most important agronomic traits, is greatly affected by architecture in rice. Here, we show that an OsPrMC3, a rice PrMC3 orthologue with a lipase or esterase domain, involves in yielding by tillering. Phenotypic analysis of T-DNA insertion mutant revealed that it has high number of tillers than wild type although height and leaf width are shorter and narrower than wild type. Size and branch number of panicle were greatly reduced in the mutant, which resulted in significant decrease of seed number per panicle and dry weight of the seeds. OsPrMC3 is highly expressed in the leaf during the early stage of development. However, it is mainly expressed in mature seed and root after flowering although its expression is detected in all of the tissues. Our result indicates that OsPrMC3 involves in leaf growth and tillering during vegetative growth and also seed development after flowering, suggesting its crucial regulatory role in yielding