A method of preparing hydrophobic porous silica includes adding an alcohol to a solvent in which a porous silica particle including a hydrophilic group is dispersed and stirring the same to form a mixture, drying the mixture including the porous silica particle in a vacuum, and condensation reacting the hydrophilic group of the porous silica particle with the alcohol on the surface of the porous silica particle to modify the surface of the porous silica particle to be hydrophobic.