Plants sense potential pathogens by recognizing conserved pathogen-associated molecular patterns (PAMPs) that cause PAMP-triggered immunity (PTI) including the generation of reactive oxygen species, callose deposition, and expression of several PTI-related genes. Acidovorax avenae is a Gam-negative bacterium that causes a seedling disease characterized by the deposition of brown stripes on the sheaths of infected plants. We previously reported that flagellin isolated from the rice avirulent A. avenae N1141 strain induces PTI, while flagellin isolated from the rice virulent A. avenae K1 strain does not induce PTI. To examine the molecular mechanism of specific PTI induction by N1141 flagellin, highly purified flagellin from N1141 or K1 strains is required. Here, we describe a high quality purification method for the A. avenae flagellins and for using it in PTI induction study.