The present invention provides polynucleotide and so on for stabilizing RNA catabolic enzyme and having function of RNA interfering.The polynucleotide is single-stranded polynucleotide regarding double strand polynucleotide comprising sense strand which corresponds to target gene and anti-sense strand which is complementary to base sequence of the sense strand as a source, and has structure formed by binding 5’ end of the anti-sense strand and 3’ end of the sense strand through linking groups having phenyl groups of phosphodiester formed on said ends.本發明係提供對RNA分解酵素安定，具有RNA干擾作用之多核苷酸等。該多核苷酸係單股多核苷酸，其係以具有：對應於標的基因之正義股多核苷酸，及具有與該正義股多核苷酸互補之鹼基序列之反義股多核苷酸之雙股多核苷酸為來源，且具有：該反義股之5’末端及正義股之3’末端藉由在上述各端形成磷酸二酯構造之含有苯基之連結基而結合成之構造。
