An interdental cleaning instrument comprising: a base part having a shape extending in a specific direction; and a cleaning part that is composed of an elastomer having a hardness lower than the hardness of the base part, covers at least a portion of the base part, and is capable of cleaning an interdental space, wherein the base part has a shaft part which has a shape that allows to be inserted in the interdental space, and has an insertion end section formed at one end in the specific direction and a base end section formed at the other end in the specific direction, and a grip part that extends from the base end section along the specific direction so as to be spaced apart from the shaft part and has a shape that can be grasped by fingers; the shaft part has a shape that can be flexurally deformed so as to allow for a displacement of the insertion end section in an axially perpendicular direction, which is perpendicular to an axial direction of the shaft part, with respect to the base end section; the cleaning part has a shape that covers a portion of the shaft part, the portion including the insertion end section and having a dimension equal to or less than a dimension of the shaft part in the axial direction, characterized in that a dimension of the base part in the axial direction is set to 35 mm or more; and at least the shape of the base part is set such that a first pressing force required to press a portion spaced 2.5 mm apart from a tip of the cleaning part in the interdental cleaning instrument to the grip part side in 10 mm vertically downward is 0.3 N or more and 1.4 N or less in a state in which a portion spaced 10 mm apart from the tip of the cleaning part in the interdental cleaning instrument to the grip part side is fixed in a posture in which the axial direction is parallel to a horizontal direction, and a second pressing force required to press a portion spaced 8.0 mm apart from the tip of the cleaning part in the interdental cleaning instrument to the grip part side in 10 mm vertically downward is 0.5 N or more and 2.5 N or less in a state in which a portion spaced 35 mm apart from the tip of the cleaning part in the interdental cleaning instrument to the grip part side is fixed in a posture in which the axial direction is parallel to a horizontal direction. a base part having a shape extending in a specific direction; and a cleaning part that is composed of an elastomer having a hardness lower than the hardness of the base part, covers at least a portion of the base part, and is capable of cleaning an interdental space, wherein the base part has a shaft part which has a shape that allows to be inserted in the interdental space, and has an insertion end section formed at one end in the specific direction and a base end section formed at the other end in the specific direction, and a grip part that extends from the base end section along the specific direction so as to be spaced apart from the shaft part and has a shape that can be grasped by fingers; the shaft part has a shape that can be flexurally deformed so as to allow for a displacement of the insertion end section in an axially perpendicular direction, which is perpendicular to an axial direction of the shaft part, with respect to the base end section; the cleaning part has a shape that covers a portion of the shaft part, the portion including the insertion end section and having a dimension equal to or less than a dimension of the shaft part in the axial direction, characterized in that a dimension of the base part in the axial direction is set to 35 mm or more; and at least the shape of the base part is set such that a first pressing force required to press a portion spaced 2.5 mm apart from a tip of the cleaning part in the interdental cleaning instrument to the grip part side in 10 mm vertically downward is 0.3 N or more and 1.4 N or less in a state in which a portion spaced 10 mm apart from the tip of the cleaning part in the interdental cleaning instrument to the grip part side is fixed in a posture in which the axial direction is parallel to a horizontal direction, and a second pressing force required to press a portion spaced 8.0 mm apart from the tip of the cleaning part in the interdental cleaning instrument to the grip part side in 10 mm vertically downward is 0.5 N or more and 2.5 N or less in a state in which a portion spaced 35 mm apart from the tip of the cleaning part in the interdental cleaning instrument to the grip part side is fixed in a posture in which the axial direction is parallel to a horizontal direction.