Humidifier for preventing pollution of humidifying water

A humidifier comprising:

• a storage water tank to store water;
• a circulating water tank to receive and store water from the storage water tank;
• a residual water tank to receive and store water from the circulating water tank;
• a supply pump configured to supply water stored in the storage water tank to the circulating water tank while the humidifier operates in a humidity mode;
• a humidifying member to receive water stored in the circulating water tank while the humidifier operates in the humidity mode;
• a circulating pump configured to supply the water in the circulating water tank to the humidifying member while the humidifier operates in the humidity mode;
• a fan configured to blow air toward the humidifying member which has received the water from the circulating water tank to evaporate the water received by the humidifying member and thereby cause water evaporated to be discharged to outside the humidifier while the humidifier operates in a humidity mode;
• an internal pipe configured to form a flow pass through which water that remains in the humidifying member is guided to the circulating water tank;
• a drainage member configured to selectively discharge the water in the circulating water tank to the residual water tank;
• and
• a controller configured to
• control the drainage member to discharge the water in the circulating water tank to the residual water tank based on the humidity mode being stopped.