Quinoxaline derivatives represented by formula (I) ** Formula ** in the formula, R1 represents C1-6 alkyl, R2 is missing, R3 represents C1-9 alkyl, which is substituted with carboxy； or C5-7 cycloalkyl, R4 represents hydrogen； hydroxy； C1-6 alkyl which is optionally substituted with hydroxy, halogen, C1-6 alkoxy, C1-6 haloalkoxy with 1 to 9 halogen, carboxy, C1-6 alkoxycarbonyl, alkanoyl, amino, amido, carbamoyl or oxo atoms； or amino which is optionally substituted with 1 to 2 substituents selected from C1-6 alkyl, C2-6 alkenyl, C2-6 alkynyl, C1-6 haloalkyl with 1 to 9 halogen atoms, alkanoyl, carbocyclic group and heterocyclic group, R5 represents hydrogen； halogen； C1-6 alkyl, C2-6 alkenyl or C1-6 alkoxy each of which is optionally substituted with hydroxy, halogen, C1-6 alkoxy, C1-6 haloalkoxy with 1 to 9 halogen, carboxy, C1-6 alkoxycarbonyl atoms , alkanoyl, amino, amido, carbamoyl or oxo； cyano or nitro, R6 and R7 each independently represents hydrogen； halogen； C1-6 alkyl, C2-6 alkenyl, C2-6 alkynyl or C1-6 alkoxy each of which is optionally substituted with hydroxy, halogen, C1-6 alkoxy, C1-6 haloalkoxy with 1 to 9 halogen atoms, carboxy , C1-6 alkoxycarbonyl, alkanoyl, amino (here the amino group may also be substituted with 1 to 2 substituents selected from C1-6 alkyl, C2-6 alkenyl, C2-6 alkynyl, C1-6 haloalkyl with 1 to 9 atoms of halogen, alkanoyl, carbocyclic group and heterocyclic group), amido, carbamoyl, oxo, carbocyclic group and heterocyclic group (here each carbocyclic group and heterocyclic group can be substituted with hydroxy, halogen, C1-6 alkyl, C2-6 alkenyl, alkynyl C2-6, C1-6 alkoxy, carboxy, C1-6 alkoxycarbonyl, amino, amido or carbamoyl)； cyano； amino which is optionally substituted with 1 to 2 substituents selected from C1-6 alkyl, C2-6 alkenyl and C2-6 alkynyl (here C1-6 alkyl, C2-6 alkenyl and C2-6 alkynyl can also be substituted independently of each other with, hydroxy, halogen, C1-6 alkoxy, C1-6 haloalkoxy with 1 to 9 halogen atoms
