An object of the present invention is to provide an endoparasite control agent comprising a carboxamide derivative represented by the following general formula or a salt thereof as an active ingredient for the purpose of providing a novel endoparasite control agent such as an anthelmintic agent or an antiprotozoal agent. General formula (I)新規な駆虫剤或いは抗原虫剤等の内部寄生虫防除剤を提供することを目的とし、下記一般式で表されるカルボキサミド誘導体又はその塩類を有効成分とする内部寄生虫防除剤を提供する。一般式(I)【化1】