A horn switch device includes a first contact member, a second contact member disposed relative to the first contact member via a spacer, a guide shaft for guiding the first and second contact members, a coil spring, and a contacting body at the distal end of an extension extending from a retainer. The items may comprise mail pieces. An axial cross-sectional area of the electrode part is equal to or larger than a cross-sectional area of the lead part in a direction perpendicular to an axis of the ceramic heater. Subsequently a check is made as to whether the item of information is defective.