In this report, we show the recognition of RNA secondary structure by exploiting a fluorescent 2,7-disubstituted 9H-xanthen-9-one derivative (2). The xanthone derivertive (2) especially bound to RNA and became non-fluorescent. Upon mixing with RRE model RNA, U-bulge RNA, or hairpin RNA, the fluorescence intensity of 2 was decreased in different intensity. The distinct fluorescent increase of 2 to each RNA seems to a good probe for The RNA structures.