. . "Disclosed herein are a novel 2-substituted adenosine derivative having the following formula [I] ##STR1## wherein R represents a hydrogen atom or a hydroxyl group, m is an integer of 2 to 7, n is 0 or an integer of 1 to 3, and R1, R2 and R3, which may be the same or different, each independently represent a hydrogen atom, a hydroxy protective group or a phosphoric acid residue, and salts thereof." . .