The present invention relates to an acid amid derivative of the formula (I) or a salt thereof: wherein A is phenyl which may be substituted by X, benzyl which may be substituted by X, naphthyl which may be substituted by X, a heterocyclic group which may be substituted by X, a fused heterocyclic group which may be substituted by X, indanyl (the indanyl may be substituted by halogen, alkyl or alkoxy) or tetrahydronaphthyl (the tetrahydronaphthyl may be substituted by halogen, alkyl or alkoxy), B is alkyl, cycloalkyl, phenyl which may be substituted by Y, a heterocyclic group which may be substituted by Y, or a condensed heterocyclic group which may be substituted by Y, each of R1 and R2 is alkyl, cyano or —CO2R14, or R1 and R2 may together form a 3- to 6-membered saturated carbocyclic ring, R3 is hydrogen, alkyl, alkoxyalkyl, alkylthioalkyl, —COR15, —S(O)mR16 or —S(O)nNR17R18, which is useful as an active ingredient of pesticides.