A cleaning tool comprising a cleaning sheet and a holder for holding the cleaning sheet, wherein: the cleaning sheet has an insertion part into which the holder is inserted, the holder includes a holding part which is inserted into the insertion part and holds the cleaning sheet, and a grip part which is connected to the holding part and designed to be held by a user, the holding part includes a connection part connected to the grip part, a tip part on a side opposite to the connection part, and an extending part extending from the connection part toward the tip part, and a part of the cleaning sheet corresponding to the extending part is thicker than a part of the cleaning sheet corresponding to the connection part in a thickness direction of the cleaning sheet when the holder is inserted into the insertion part and holds the cleaning sheet, wherein the extending part comprises two elongate members, and the two elongate members are connected to each other at the connection part, wherein each of the elongate members comprises two elastically deformable elastic members (635, 636), and the two elastic members are connected to each other at the connection part side and the tip part side, and are spaced apart from each other in an intermediate region between the connection part and the tip part in the thickness direction when the holder is inserted into the insertion part and holds the cleaning sheet, characterized in that the first elastic member and the second elastic member are movable by an external force in a direction to shorten the distance therebetween in a cleaning element holder thickness direction so that an elastic member connecting virtual line connecting the first elastic member and the second elastic member is made parallel to a cleaning element holder transverse direction. the cleaning sheet has an insertion part into which the holder is inserted, the holder includes a holding part which is inserted into the insertion part and holds the cleaning sheet, and a grip part which is connected to the holding part and designed to be held by a user, the holding part includes a connection part connected to the grip part, a tip part on a side opposite to the connection part, and an extending part extending from the connection part toward the tip part, and a part of the cleaning sheet corresponding to the extending part is thicker than a part of the cleaning sheet corresponding to the connection part in a thickness direction of the cleaning sheet when the holder is inserted into the insertion part and holds the cleaning sheet, wherein the extending part comprises two elongate members, and the two elongate members are connected to each other at the connection part, wherein each of the elongate members comprises two elastically deformable elastic members (635, 636), and the two elastic members are connected to each other at the connection part side and the tip part side, and are spaced apart from each other in an intermediate region between the connection part and the tip part in the thickness direction when the holder is inserted into the insertion part and holds the cleaning sheet, characterized in that the first elastic member and the second elastic member are movable by an external force in a direction to shorten the distance therebetween in a cleaning element holder thickness direction so that an elastic member connecting virtual line connecting the first elastic member and the second elastic member is made parallel to a cleaning element holder transverse direction. the holding part includes a connection part connected to the grip part, a tip part on a side opposite to the connection part, and an extending part extending from the connection part toward the tip part, and a part of the cleaning sheet corresponding to the extending part is thicker than a part of the cleaning sheet corresponding to the connection part in a thickness direction of the cleaning sheet when the holder is inserted into the insertion part and holds the cleaning sheet,