The information medium of the present invention is provided with a lead-in region and a data region in which information signals can be recorded, wherein the lead-in region has a recordable portion in which information signals can be recorded. The fluxer includes an enclosure that defines a chamber where the object is fluxed. In addition, the selection unit selects either of a first precoding system carrying out linear processing with respect to the plurality of series of data or a second precoding system carrying out nonlinear processing with respect to the plurality of series of data. The metal films are symmetrically coated on two predetermined sides of four sides of the probe body while being spaced apart from each other.