A clothes treatment apparatus comprising: a cabinet partitioned into a treatment chamber for allowing clothes to be hung therein, a cycle chamber for allowing machinery to be installed therein, and a tank installation space configured to allow a water supply tank and a drainage tank to be disposed therein; a door for opening and closing the cabinet; a steam unit disposed in the cycle chamber for supplying steam into the treatment chamber; a heat pump unit disposed in the cycle chamber for circulating air in the treatment chamber and conditioning the air that is circulated; a control unit controlling at least one of the steam unit or the heat pump unit; a water supply level sensor configured to sense a level of water stored in the water supply tank; and a drainage level sensor configured to sense a level of water stored in the drainage tank, wherein the water supply tank is separably installed in the tank installation space, and is connected to the steam unit, and is configured to supply water to the steam unit, and wherein the drainage tank is separably installed in the tank installation space, configured to store condensed water generated in at least one selected from between the treatment chamber and the heat pump unit, characterized in that wherein the water supply level sensor comprises: a float case fixed in the water supply tank; a float installed in the float case such that the float is movable upward and downward in the float case by buoyancy depending on the level of water stored in the water supply tank; and a sensor installed at the cabinet and configured for sensing a magnetic force of the float, and configured to fail to sense the float when the float moves lower than a minimum level of water stored in the water supply tank, wherein the minimum level is a water level at which it is possible to supply an amount of steam corresponding to one cycle, wherein when the float moves lower than the sensor and the sensor fails to sense the float during a cycle being performed, the control unit outputs a water deficiency signal and controls the steam unit to complete the cycle. a cabinet partitioned into a treatment chamber for allowing clothes to be hung therein, a cycle chamber for allowing machinery to be installed therein, and a tank installation space configured to allow a water supply tank and a drainage tank to be disposed therein; a door for opening and closing the cabinet; a steam unit disposed in the cycle chamber for supplying steam into the treatment chamber; a heat pump unit disposed in the cycle chamber for circulating air in the treatment chamber and conditioning the air that is circulated; a control unit controlling at least one of the steam unit or the heat pump unit; a water supply level sensor configured to sense a level of water stored in the water supply tank; and a drainage level sensor configured to sense a level of water stored in the drainage tank, wherein the water supply tank is separably installed in the tank installation space, and is connected to the steam unit, and is configured to supply water to the steam unit, and wherein the drainage tank is separably installed in the tank installation space, configured to store condensed water generated in at least one selected from between the treatment chamber and the heat pump unit, characterized in that wherein the water supply level sensor comprises: a float case fixed in the water supply tank; a float installed in the float case such that the float is movable upward and downward in the float case by buoyancy depending on the level of water stored in the water supply tank; and a sensor installed at the cabinet and configured for sensing a magnetic force of the float, and configured to fail to sense the float when the float moves lower than a minimum level of water stored in the water supply tank, wherein the minimum level is a water level at which it is possible to supply an amount of steam corresponding to one cycle, wherein when the float moves lower than the sensor and the sensor fails to sense the float during a cycle being performed, the control unit outputs a water deficiency signal and controls the steam unit to complete the cycle. a float case fixed in the water supply tank; a float installed in the float case such that the float is movable upward and downward in the float case by buoyancy depending on the level of water stored in the water supply tank; and a sensor installed at the cabinet and configured for sensing a magnetic force of the float, and configured to fail to sense the float when the float moves lower than a minimum level of water stored in the water supply tank, wherein the minimum level is a water level at which it is possible to supply an amount of steam corresponding to one cycle, wherein when the float moves lower than the sensor and the sensor fails to sense the float during a cycle being performed, the control unit outputs a water deficiency signal and controls the steam unit to complete the cycle.