A laundry dryer comprising: a cabinet forming an outer body; a drum rotatably supported inside the cabinet and supplied with hot air and steam therein; a steam unit placed inside the cabinet and to generate the steam; a storage tank placed inside the cabinet and to store water to be supplied to the steam unit therein; a tank housing placed inside the cabinet and to separably accommodate the storage tank; and a floater placed inside the storage tank and to move in a vertical direction according to a level of water stored in the storage tank, a floater sensor installed in the tank housing for detecting a vertical position of the magnet embedded in the floater, wherein the floater includes a body portion having a first outer surface (815a1) and a second outer surface (815a2) formed parallel to each other and spaced apart by a first interval (Hf), a third outer surface (815a3) and a fourth outer surface (815a4) formed parallel to each other and spaced apart by a second interval (Wf) and a fifth outer surface (815a5) and a sixth outer surface (815a6) formed parallel to each other and spaced at a third interval (Lf), wherein, inside the storage tank, the first outer surface (815a1) is placed to become an upper surface in the vertical direction and the second outer surface (815a2) is placed to become a lower side surface in the vertical direction, based on a state in which the storage tank is accommodated in the tank housing, and wherein the first interval (Hf) is smaller than the second interval (Wf) or the third interval (Lf), wherein the floater further includes a magnet in a hexahedral shape embedded in the body portion, and the body portion includes a magnet receiving unit having a shape corresponding to the shape of the magnet and in which the magnet is inserted, wherein the floater sensor includes a sensing unit extending in the vertical direction between a lowest position and a highest position of the magnet. a cabinet forming an outer body; a drum rotatably supported inside the cabinet and supplied with hot air and steam therein; a steam unit placed inside the cabinet and to generate the steam; a storage tank placed inside the cabinet and to store water to be supplied to the steam unit therein; a tank housing placed inside the cabinet and to separably accommodate the storage tank; and a floater placed inside the storage tank and to move in a vertical direction according to a level of water stored in the storage tank, a floater sensor installed in the tank housing for detecting a vertical position of the magnet embedded in the floater, wherein the floater includes a body portion having a first outer surface (815a1) and a second outer surface (815a2) formed parallel to each other and spaced apart by a first interval (Hf), a third outer surface (815a3) and a fourth outer surface (815a4) formed parallel to each other and spaced apart by a second interval (Wf) and a fifth outer surface (815a5) and a sixth outer surface (815a6) formed parallel to each other and spaced at a third interval (Lf), wherein, inside the storage tank, the first outer surface (815a1) is placed to become an upper surface in the vertical direction and the second outer surface (815a2) is placed to become a lower side surface in the vertical direction, based on a state in which the storage tank is accommodated in the tank housing, and wherein the first interval (Hf) is smaller than the second interval (Wf) or the third interval (Lf), wherein the floater further includes a magnet in a hexahedral shape embedded in the body portion, and the body portion includes a magnet receiving unit having a shape corresponding to the shape of the magnet and in which the magnet is inserted, wherein the floater sensor includes a sensing unit extending in the vertical direction between a lowest position and a highest position of the magnet.