To provide an ionization device enhanced in reliability by preventing useless discharge from easily occurring.

A connection member includes a hollow electrode connection pipe for electrically connecting high-voltage distribution boards by inserting them into the inside thereof; the respective high-voltage distribution boards are inserted from both sides of opening ends of each electrode connection pipe by connecting casing members to each other through the connection member; and the high-voltage distribution boards can be structured to be electrically connected to each other through the electrode connection pipe by bringing parts in the vicinities of end edges of the high-voltage distribution boards into contact with the inside surface of the electrode connection pipe. Thereby, in connection of the high-voltage distribution boards of the casing members adjacent to each other, since edge parts can be electrically eliminated by connecting them in a state where the edge parts of end edges easily causing discharge are housed in the electrode connection pipe, this ionization device enhanced in reliability by extremely reducing useless discharge can be provided.