An ozonizer in which a pair of plate-like electrode plates are arranged opposite to each other so as to form a discharge space therebetween, and ceramic dielectric layers are arranged on the surface on the side of the discharge space of said electrode plates, wherein a plate-like anode 4 is arranged between the dielectrics 31 and 32, extreme ends 41 and 42 having sharp extreme ends of a number of protrusions are formed on both surfaces of the anode 4, the anode 4 is arranged between the dielectrics 41 and 42 in a state where the extreme ends 41 and 42 are in contact with the surfaces of the dielectrics 31 and 32 on both sides, the anode 4 is formed with a number of through-holes extending through both surfaces, and the anode being formed of expanded metal.