Printer and information writing method

An information writing method that is a method of writing information in a radio tag in a printer including:

• a platen configured to convey a paper sheet in which the radio tag is embedded;
• a print head configured to print information on the paper sheet;
• a first antenna that is arranged upstream of the print head in a direction of conveyance of the paper sheet, the first antenna configured to write information in the radio tag;
• and
• a second antenna that is arranged upstream of the first antenna in the direction of conveyance of the paper sheet, the second antenna configured to write information in the radio tag;
• the method comprising:
• a first transmission including transmitting a signal using the second antenna to the radio tag, the signal containing tag identification information for discriminating the radio tag from another radio tag;
• and
• a second transmission including transmitting a signal using the first antenna to the radio tag to which the signal including the tag identification information has been transmitted by the first transmission, the signal containing the tag identification information and writing information.