To understand the plant-pathogen interaction comprehensively, it is valuable to monitor the gene expression profiles of both interacting organisms simultaneously in the same infected plant tissue. Using RNA-Seq, we analyzed the mixed transcriptome of rice and blast fungus in infected leaves at 24 hours post-inoculation. We demonstrated that our method detected the gene expression of both the host plant and pathogen simultaneously in the same infected leaf blades in natural infection conditions without any artificial treatments. Using compatible (Ina86-137) and incompatible (P91-15B) fungal strains as pathogens, we revealed the differential expression profiles of the compatible and incompatible interactions and observed that the responsive gene expression was more drastic in the incompatible interaction. Our mixed transcriptome analysis is useful for the simultaneous elucidation of the tactics of host plant defense and pathogen attack.