The present invention provides a novel isoquinoline-6-sulfonamide derivative that is useful as a medicine. The present invention provides an isoquinoline-6-sulfonamide derivative represented by Formula (1), a salt thereof, or a solvate of the derivative or the salt, wherein R1 and R2 each independently represent a hydrogen atom, or the like R3 and R4 each independently represent a hydrogen atom, an alkyl group, or the like R5 represents a hydrogen atom, an optionally substituted alkyl group, an optionally substituted alkenyl group, an optionally substituted alkynyl group, an optionally substituted cycloalkyl group, an optionally substituted alkanoyl group, or the like and A represents a linear or branched alkylene group having 2 to 6 carbon atoms.
