NOVELTY - A gas-generation apparatus has anode electrode which generates oxygen gas from the electrolyte solution, cathode electrode which generates hydrogen gas from hydrogen ion generated with the electrolyte solution, and electron, photocatalyst content layer, through-holes and gas accommodating unit which accommodates the oxygen gas or hydrogen gas that passed the through-hole. The through-hole does not allow the electrolyte solution to pass through, and allows the generated oxygen gas or hydrogen gas to pass through.    USE - Gas-generation apparatus for generating oxygen gas and/or hydrogen gas (claimed).    ADVANTAGE - The oxygen gas and/or hydrogen gas is efficiently produced using the gas-generation apparatus with visible light.    DETAILED DESCRIPTION - A gas-generation apparatus has anode electrode which generates oxygen gas from the electrolyte solution, cathode electrode which generates hydrogen gas from hydrogen ion generated with the electrolyte solution, and electron, photocatalyst content layer containing primary photocatalyst which generates oxygen gas from electrolyte solution, and/or secondary photocatalyst which generates hydrogen gas by photocatalytic reaction using visible light, through-holes which is provided in at least one of the anode electrode or cathode electrode and gas accommodating unit which accommodates the oxygen gas or hydrogen gas that passed the through-hole. The through-hole does not allow the electrolyte solution to pass through, and allows the generated oxygen gas or hydrogen gas to pass through. Oxygen gas and/or hydrogen gas is generated from the electrolyte solution containing water using gas-generation apparatus. An INDEPENDENT CLAIM is included for gas production method, which involves irradiating visible light of photocatalyst to the photocatalyst containing layer containing the primary photocatalyst which produces oxygen gas from the electrolyte solution, and/or secondary photocatalyst which produces hydrogen gas by photocatalytic reaction using visible light, and collecting oxygen gas produced with the anode electrode, or hydrogen gas produced with the cathode electrode through through-holes provided in anode electrode or cathode electrode.