Conventional many fungicidal compositions have had practical problems suchthat either a preventive effect or a curing effect is inadequate, the residualeffect tends to be inadequate, or the controlling effect against plantdiseases tends to be inadequate depending upon the application site, and afungicidal composition to overcome such problems has been desired. The presentinvention provides a fungicidal composition containing an acid amidederivative of the formula (I) or a salt thereof, as an active ingredient:wherein A is phenyl which may be substituted, benzyl which may be substituted,naphthyl which may be substituted, heterocyclic ring which may be substituted,fused heterocyclic ring which may be substituted, or the like； B isheterocyclic ring which may be substituted, fused heterocyclic ring which maybe substituted, or naphthyl which may be substituted； each of R1 and R2 whichare independent of each other, is alkyl, or the like； R3 is hydrogen, or thelike； each of W1 and W2 which are independent of each other, is oxygen orsulfur.
