Abstract: A high-precision, multi-port compatible, relative correction method and apparatus for correcting measurement errors covering an increase in the number of ports of a non-coaxial electronic component, in which a relative correction adapter 31 is provided that is formed of a two-port network connected to each port of a production test fixture 5B adjacent to a measurement apparatus. The relative correction adapter has a characteristic that modifies the electrical characteristics generated by the production test fixture 5B having an electronic component under test mounted thereon into electrical characteristics generated by a standard test fixture 5A having the electronic component under test mounted thereon. An error factor of the relative correction adapter 31 is identified from a standard test fixture measurement value and a production test fixture measurement value of a correction data acquisition specimen 11B.