Provided is a cooling device including a valve structure including a temperature-responsive material that changes in volume in response to changes in temperature, a supporting structure, which is joined to the valve structure and supports the valve structure, and a solvent which contacts the valve structure, wherein a portion of the solvent contacts the valve structure and another portion of the solvent is externally exposed, the valve structure changes in volume in response to changes in temperature and thereby regulating the externally exposed surface area of the solvent.