The present invention provides a pesticide composition comprising a pesticidalactive ingredient and a compound represented by chemical formula (I) orchemicalformula (II)R-O-(EO)w-(PO)x-(EO)y-(PO)z-H (I)R-O-(PO)w-(EO)x-(PO)y-(EO)z-H (II)(wherein, EO represents an ethyleneoxy group, PO represents a propyleneoxygroup, Rrepresents an alkyl or alkenyl group having 8 to 20 carbons, w represents onaverage aninteger in the range of 1 to 25, x represents on average an integer in therange of 1 to 25,y represents on average an integer in the range of 1 to 25, and z representson average aninteger in the range of 1 to 25). Further the present invention provides amethod forpotentiating the efficacy of the pesticidal active ingredient comprising usinga compoundrepresented by chemical formula (I) or chemical formula (II) in combinationwith apesticidal active ingredient.
