[Problem] To provide a novel triazinone compound which has an inhibitory activity on a T-type voltage-dependent calcium channel and is useful particularly for the treatment of pain. [Solution] Provided is a novel triazinone compound represented by formula (I) (wherein each substituent is as defined in detail in the text R1 represents a hydrogen atom, a C1-6 alkoxy group or the like L1 and L2 independently represent a single bond, NR2 or the like L3 represents a C1-6 alkylene group or the like A represents a C6-14 aryl group which may be substituted, a 5- to 10-membered heteroaryl group or the like B represents a C3-11 cycloalkylene group or the like and D represents a C6-14 aryl group which may be substituted, a 5- to 10-membered heteroaryl group or the like), a tautomer or a pharmaceutically acceptable salt of the compound, or a solvate of the compound, the tautomer or the pharmaceutically acceptable salt.
