Interactions between established pioneer plant species and soils are main driver of N and P availabilities in early succession in volcano. In this study, we examined soil N and P along vegetation development and differences between growing two early successional species; Alnus sieboldiana (AS) and Miscanthus condensatus (MC), on volcanic devastated sites formed after the 2000-yr eruption in Miyake-jima Island. We analyzed total N in soil as soil N and available phosphate in soil by Truog method as soil P. Both soil N and P showed an increasing trend along vegetation development. Soil N was higher under AS than MC. The high N under AS is caused by N₂ fixation ability of the species. On the other hand, there was no significant difference in soil P between plant species. Effects of plant species on the increase pattern of soil N and P with vegetation development was different between AS and MC. This reflects that difference in origin of the two nutrients: P from mineral and N from rain and/or N₂ fixation process.