The present invention provides a nematocide containing, as an active ingredient, an N-2-(pyridyl)ethylcarboxamide derivative represented by the formula (I):wherein Ar is a substituted phenyl group having one or more, the same or different substituents selected from a halogen atom, a (C1-C6)alkyl group, a halo(C1-C6)alkyl group, a (C1-C6)alkylthio group, a halo(C1-C6)alkylthio group, a (C1-C6)alkoxy group and a halo(C1-C6)alkoxy group, and the like, X may be the same or different, and is a hydrogen atom, a halogen atom, a (C1-C6)alkyl group, a halo(C1-C6)alkyl group, and the like, and n is the integer 0 to 4, or a salt thereof, and a method of controlling nematodes, including applying the above compound. The present invention can provide a nematocide or a method of controlling nematodes that exerts a reduced impact on the global environment, exhibits a broad nematode control spectrum at low application rates, and has an excellent nematode control effect.