[Problem] To provide a base part, an interdental cleaning tool, and a method for manufacturing the interdental cleaning tool, capable of preventing bending of a shaft part when a resin material is filled from an insertion end. [Solution] A base part includes a shaft part (20) and a grip part (30). The base part is used for forming an interdental cleaning tool by filling, inside a metal mold having a shape that forms a filling space around the shaft part (20), a resin material into the filling space with the shaft part (20) clamped by a holding pin. The shaft part (20) includes a first guide groove (24) formed on one side with respect to an axially parallel plane and a second guide groove (26) formed on the other side with respect to the axially parallel plane. The first guide groove (24) and the second guide groove (26) extend in the axial direction from an insertion end (22a) toward a base end and have a shape recessed toward the center of the shaft part (20) from the outer peripheral face of a region other than the first guide groove (24) and the second guide groove (26) in the shaft part (20).
