The present invention relates to a desalination apparatus and a desalination method using the same. In one specific embodiment, the desalination apparatus comprises: a forward osmosis unit having a draw-solution part into which seawater flows, and a raw water part into which raw water flows, and having an osmosis membrane, formed between the draw solution part and the raw water part, so as to respectively generate first treated water and first concentrated water; a capacitive deionization unit, which is connected to the draw solution part through a first inflow passage, and into which the first treated water of the draw solution part flows so as to generate second treated water; and an electrodialysis unit, which is connected to the raw water part through a second inflow passage, and into which the first concentrated water of the raw water part flows so as to generate third treated water.