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 (SF) installed in the tank housing for detecting a vertical position of the magnet (M) 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 (M) 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 (M) and in which the magnet (M) is inserted, wherein the floater sensor (SF) includes a sensing unit (SF1) extending in the vertical direction between a lowest position and a highest position of the magnet (M). 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 (SF) installed in the tank housing for detecting a vertical position of the magnet (M) 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 (M) 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 (M) and in which the magnet (M) is inserted, wherein the floater sensor (SF) includes a sensing unit (SF1) extending in the vertical direction between a lowest position and a highest position of the magnet (M). <EOS>