An arsenic-hyperaccumulater, Pteris vittata, has been considered as an environmental friendly-method to clean up arsenic-contaminated water. Although P. vittata accumulates high amount of arsenic up to approximately 2% of its dry-weight, the influence of senescence and As accumulation on each other, especially the extent the fern accumulates arsenic without cell death is not clearly understood. XSAM analysis showed that As accumulation in a mature leaflet was not higher than that in a young leaflet. Chlorophyll content and Ca level of the frond (leaf) was measured as indicators of (metal) metalloid stress. In the results, there was correlation of Ca level and As accumulation while there was no correlation between chlorophyll content and As accumulation. XANES analysis showed that at root top, arsenate was dominant species among ferns incubated for various periods of time. On the other hand, at root tips, arsenate abundance was gradually increased as incubation period was increased.