An interdental cleaning tool comprising: a base portion made of a synthetic resin; and a soft portion made of an elastomer that covers at least a part of the base portion, the base portion including a handle base portion, and a core base portion that has an elongated shaft-shape and connects continuously to a tip end portion of the handle base portion, the soft portion having at least a cleaning soft portion that covers the core base portion, the handle base portion constituting a handle portion serving as a grip, and the core base portion and the cleaning soft portion which constitute a cleaning portion for interdental cleaning, wherein a plurality of cleaning portion recesses which penetrate the cleaning soft portion and form recesses in the core base portion are formed on each of a first side portion and a second side portion of the cleaning portion at an interval in an axial direction of the cleaning soft portion, and at least one of the plurality of cleaning portion recesses is formed so that an opening of the core base portion recess formed in the core base portion has a shape elongated in the axial direction of the cleaning portion, wherein at least one set of two cleaning portion recesses among plural sets of the cleaning portion recesses paired between the first side portion and the second side portion is formed at an interval in the axial direction of the cleaning portion so as to be avoided from overlapping each other in a circumferential direction of the cleaning portion, the at least one set of the cleaning portion recesses formed at the interval in the axial direction of the cleaning portion has, therebetween, an interval in the axial direction of the cleaning portion, the interval being set to one fourth or more of a maximum axial length of the cleaning portion recesses. a base portion made of a synthetic resin; and a soft portion made of an elastomer that covers at least a part of the base portion, the base portion including a handle base portion, and a core base portion that has an elongated shaft-shape and connects continuously to a tip end portion of the handle base portion, the soft portion having at least a cleaning soft portion that covers the core base portion, the handle base portion constituting a handle portion serving as a grip, and the core base portion and the cleaning soft portion which constitute a cleaning portion for interdental cleaning, wherein a plurality of cleaning portion recesses which penetrate the cleaning soft portion and form recesses in the core base portion are formed on each of a first side portion and a second side portion of the cleaning portion at an interval in an axial direction of the cleaning soft portion, and at least one of the plurality of cleaning portion recesses is formed so that an opening of the core base portion recess formed in the core base portion has a shape elongated in the axial direction of the cleaning portion, wherein at least one set of two cleaning portion recesses among plural sets of the cleaning portion recesses paired between the first side portion and the second side portion is formed at an interval in the axial direction of the cleaning portion so as to be avoided from overlapping each other in a circumferential direction of the cleaning portion, the at least one set of the cleaning portion recesses formed at the interval in the axial direction of the cleaning portion has, therebetween, an interval in the axial direction of the cleaning portion, the interval being set to one fourth or more of a maximum axial length of the cleaning portion recesses.