A method for treating water using a salt desorption process of gas hydrates according to the present invention includes: (a) introducing water containing impurities and a plurality of guest gases into a reactor; (b) forming gas hydrates by causing the water and the plurality of guest gases to react under a first condition; and (c) dissociating a gas hydrate of one guest gas from among the plurality of guest gases by changing the first condition to a second condition, wherein the first condition refers to temperature and pressure conditions under which all of the plurality of guest gases form gas hydrates and the second condition refers to temperature and pressure conditions under which the gas hydrate of the one guest gas from the mixed gas hydrates is dissociated.