The present invention provides a bactericide which contains a 2-aminonicotinic acid ester derivative as an active ingredient. The active ingredient of the present invention is represented by formula [I]. (In the formula, R1 represents a hydrogen atom or a C1-C4 alkyl group, R2 represents a hydrogen atom or a C1-C4 alkyl group, and R1 and R2 may combine together to form an alkylene chain R3 represents a hydrogen atom or a C1-C4 alkyl group R4 represents a hydrogen atom, a cyano group or a C1-C4 alkyl group each of R5 and R6 independently represents a hydrogen atom, a halogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, a C1-C4 alkylthio group, a C1-C4 alkylsulfinyl group, a C1-C4 alkylsulfonyl group, a nitro group, a cyano group, a C1-C4 haloalkyl group, a C1-C4 haloalkoxy group or a C1-C4 haloalkylthio group and each of A and B independently represents a methine group (CH) or a nitrogen atom.)
