9-Amino-2-methoxy-6-nitroacridine (1a) is conjugated with oligonucleotide for site-selective RNA hydrolysis. When this conjugate forms a duplex with complementary RNA, the phosphodiester linkage of the RNA in front of 1a is activated and selectively hydrolyzed by Lu(III) ion. Covalent fixation of the metal ion to sequence-recognizing moiety is unnecessary. The site-selective hydrolysis by this conjugate is 2.2 times as fast as that by the oligonucleotide bearing 9-amino-6-chloro-2-methoxyacridine (1b), which hitherto has been the most active for the RNA activation. The acridine derivative 1a is more acidic than 1b, and thus is more effective as acid catalyst for the RNA hydrolysis.