NOVELTY - The gas production apparatus (800) has a first electrode (310), a second electrode (320) containing a photocatalyst, and a bottomed container (110) forming a storage chamber (112) in which the object electrode is accommodated. The chamber is closed and a separation membrane (330) which restricts the passage of gas and separates hydrogen and oxygen gases is provided. The object electrode contains a protruding terminal (314) which is inserted into a through-hole (132) formed in the container, such that the through-hole supports the object electrode from the inside of the container.    USE - Gas production apparatus for producing hydrogen gas or oxygen gas using a photocatalyst, from electrolyte solution containing water, in gas production system used with electric power generation system, fuel cell, etc.    ADVANTAGE - The structure for supporting an electrode is simplified. Manufacture of gas production apparatus is made easy, since an object electrode is easily accommodated in a container by changing the shape of an object electrode using a variable portion. The electrolyte solution is increased, so that efficiency fall of gas production is suppressed.    DETAILED DESCRIPTION - The object electrode contains a variable portion which is a portion which changes the shape of object electrode. The length of the insertion direction of object electrode is longer than the length of the insertion direction of the opening. The container has a recessed portion (114) which supports the object electrode by inserting the edge portion away from the terminal of the object electrode. The object electrode is the first electrode and it is an electrode for producing hydrogen gas.    DESCRIPTION OF DRAWING(S) - The drawing shows a sectional view of the structure of gas production apparatus. (Drawing includes non-English language text)    Bottomed container (110)    Storage chamber (112)    Recessed portion (114)    Through-hole (132)    Electrodes (310,320)    Terminal (314)    Separation membrane (330)    Gas production apparatus (800)