A compound of the formula (I) or a salt thereof: where Y is N or CR1, R1, R3, and R4 are the same or different from each other and are each C1-6 alkyl which may be substituted with one or more substituents selected from the group consisting of halogen, -OH, -O-C1-6 alkyl, -O-halogen-C1-6 alkyl and -NR9R10, H, or halogen, R2 is C1-6 alkyl which may be substituted with one or more substituents selected from the group consisting of halogen and cyano, and R2 may be combined with R1 to form - (CH2) n -, or R2 may be combined with R3 to form - (CH2) n -, n is 2 or 3, R51 and R52 are the same or different from each other and are C1-6 alkyl which may be substituted with one or more substituents selected from Group G2, cycloalkyl which may be substituted with one or more substituents selected from Group G1, or H, and in addition, R51 and R52 may be combined with a nitrogen atom to which they are linked to form cyclic amino which may be substituted with a or more substituents selected from Group G1, X is a bond, -NR11-, or -NR11-O-, R11 is H or C1-6 alkyl, R6 is C1-6 alkyl which may be substituted with one or more substituents selected from Group G4, or cycloalkyl which may be substituted with one or more substituents selected from group G3, in addition, when -X-R6- is NR11-R6, R6 and R11 may be combined with a nitrogen atom to which they are linked to form amino cyclic which may be substituted with one or more substituents selected from Group G3, R7 and R8 are the same or different from each other and are each C1-6 alkyl which may be substituted with one or more substituents selected from the group consisting of halogen, - OH, and -O-halogen-C1-6 alkyl, or H, Group G1 and Group G3 include C1-6 alkyl, halogen-C1-6 alkyl, halogen, -OH, -O-C1-6 alkyl, -O- halogen C1-6 alkyl, and -NR9R10, Group G2 and Group G4 include halogen, -OH, -O-C1-6 alkyl, -O-halogen-C1-6 alkyl, cycloalkyl or which may be substituted with one or more halogen atoms, -O- (cycloalkyl which may be substituted
