The architecture of rice panicle is primarily determined by the arrangement of branches and spikelets, and it directly affects grain yield. We identified a mutant for panicle apical abortion from a japonica cultivar Hwacheongbyeo treated with N-methyl-N-nitrosourea. Under normal growth conditions, the mutant had multiple abnormal phenotypes, such as a slight reduction in plant height, narrow and dark green leaf blades, and small erect panicles with clear panicle apical abortion compared to the wild-type plants. Genetic analysis revealed that the panicle apical abortion was controlled by a single recessive gene, which is tentatively designated as paa. The paa gene was fine mapped at an interval of 71 kb flanked by STS markers aptn3 and S6685-1 at the long arm of chromosome 4. Sequence analysis of the candidate genes within the delimited region showed a single base-pair change corresponding to an amino acid substitution from glycine to glutamic acid. We expect that the paa gene will be a clue to uncover the molecular mechanism of panicle apical abortion and to maintain the panicle identity for grain yield in rice breeding programs.