An endophyte was isolated from the root nodule of alnus hirsuta. The isolated endophyte was identified as a Frankia sp. through morphological characteristics. Their infectivity and effectivity were confirmed by nitrogen-fixing root nodules induced on inoculated Alnus seedlings. Reisolated endophyte from the induced nodule showed identical morphological characteristics as the first isolate, showing the nodule was induced by the first isolate. Consequently, the first isolate was confirmed as a true symbiont of Almus hirsuta root nodule. The isolate was designated as a Frankia SNU 014201 strain.