The brown planthopper, Nilaparvata lugens Stal (Hemiptera: Delphacidae), is a serious insect pest of rice (Oryza sativa L.). It is known that several wild rice and some Indica Group rice cultivars carry brown planthopper resistance genes. The brown planthopper resistance locus BPH1 has been used for the development of brown planthopper resistance rice in Southeast Asia. Bph1 and Bph2 are considered to be different resistance alleles in the same BPH1 locus, and each resistance allele has a different specificity against different brown planthopper biotypes. The first and second intronic DNA sequences in the BPH1 locus, which are derived from the Indica Group rice cultivar ADR52, wild rice Oryza officinalis and the Japonica Group rice cultivar Nipponbare, were analyzed to find insertion and deletion (InDel) polymorphisms. Based on this InDel polymorphisms information, we developed a multiplex polymerase chain reaction (PCR) method that enables the simultaneous identification of three alleles from the BPH1 locus: Bph1, Bph2 and a Japonica-type allele. Our method will be useful for future breeding research because it facilitates the classification of allele types in the BPH1 locus.