A cutting tool for boring that is attached to a machining apparatus and used for cutting a hole on a large-diameter side of a stepped hole of a workpiece is provided. The cutting tool for boring is a set of two tools, and each cutting tool for boring in the set of two includes a shaft part, a cutting blade laterally protruding from the respective shaft parts, and an abutment surface formed at the tip of each shaft part and used to cause the tips of the respective shaft parts to butt against each other. Each cutting tool for boring performs cutting while the two cutting tools for boring rotate integrally around the center line of the shaft parts in a coupled state in which the tips of the cutting tools for boring are butted together.