A novel adenine compound represented by the formula (1): wherein A represents an (un)substituted aromatic carbocycle or (un)substituted aromatic heterocycle； L 1 and L 2 each independently represents straighted or branched alkylene, etc.； R 1 represents halogen, (un)substituted alkyl, (un)substituted alkenyl, (un)substituted alkynyl, (un)substituted cycloalkyl, (un)substituted aryl, or (un)substituted heteroaryl； R 2 and R 3 each independently represents hydrogen, or (un)substituted alkyl, (un)substituted alkenyl, (un)substituted alkynyl, (un)substituted cycloalkyl, (un)substituted saturated heterocycle, (un)substituted aryl, or (un)substituted heteroaryl, or R 2 combines together with L 2 or R 3 to form (un)substituted 4- to 8-membered nitrogen-containing saturated heterocycle； X is oxygen, sulfur, SO, SO 2 , NR 7 , NR 7 CO wherein R 7 is hydrogen or alkyl, or a single bond； provided that X is a single bond when R 1 is halogen, or a pharmaceutically acceptable salt thereof. The compound and salt are useful as a medicine.
