PROBLEM TO BE SOLVED: To provide a technique for isolating a rice hybrid weakness causative gene, and artificially inducing hybrid weakness or hypersensitive cell death by utilizing the gene. SOLUTION: The hybrid weakness causative gene is the combination of a first gene and a second gene as a pair of the genes, and exhibits a phenotype of the hybrid weakness or the hypersensitive cell death when both are expressed. The first gene is HWC1 encoding a specific amino acid sequence, and the second gene is HWC2 encoding a specified amino acid sequence. COPYRIGHT: (C)2011,JPO&INPIT