In a hydrogen generation apparatus, water is electrolyzed by an electrolysis electrode part, and a porous ceramic catalyst may be combined with the oxygen generated at the time of electrolysis to prevent the generation of ozone. In addition, when the resistance value of water is measured, the change in resistance according to the kind of electrolyte dissolved in water and the concentration of the corresponding electrolyte is measured, and then, the applied voltage is varied depending on the measured resistance value, so that the water is electrolyzed in the optimal quantity according to the ingredient dissolved in the water, thereby preventing the generation of components harmful to the human body.
