<p>The invention discloses quinoxaline derivatives or salts thereof having PDE9-inhibiting activity and being useful as treating agent of dysuria and the like, which are represented by the formula (I)
in the formula,
R 1 and R 2 each independently are hydrogen or C 1-6 alkyl;
R 3 is C 1-9 alkyl or C 2-9 alkenyl each of which may be substituted with carboxy or C 1-6 alkoxycarbonyl;
R 4 is hydrogen;
R 5 and R 8 are hydrogen;
R 6 and R 7 each independently are hydrogen; C 1-6 alkyl or C 1-6 alkoxy each of which is optionally substituted with halogen;
X is O;
A 1 , A 2 and A 3 are C,
or a salt thereof.</p>
