a method of measuring a range from a reader unit to a non - contacted ic medium , includes : transmitting an inquiry signal at a first frequency from the reader unit to the non - contacted ic medium ; causing the non - contacted ic medium to perform modulation to modulate the first frequency by using a second frequency to obtain a modulated frequency , and causing the non - contacted ic medium to respond to a response signal at the modulated frequency ; causing the reader unit to receive the response signal to acquire a plurality of frequency components ; calculating a phase difference between signals of at least two of the acquired plurality of frequency components ; and measuring the range by using the phase difference .