In a steam cooker, a tray-shaped case of a steam temperature-raising device has a recessed part into which steam from a steam generator flows through steam supply ports provided in a first sidewall. In the method, an integrated circuit substrate having top and bottom surfaces is provided. Ozonated liquid containing ozone microbubbles is injected through an injection manifold positioned within the injection section of the tank. The contact member is in surface-contact with the non-image forming area and is not contacting with the image forming area. The switching circuit maintains each of the share line voltages equally at an intermediate voltage level that is between the share line voltages.