The running tests at the Yamanashi Maglev Test Line started in April 1997 by using a completed 18.4-km guideway to investigate the performance of brake and superconducting magnets and the characteristics of vehicle dynamics. These tests verified the dynamics between two trains passing each other at high speeds, the performance of the control system of multiple power conversion stations, and the influence of environments. A maximum speed of 552 km/h has been attained in these tests. The performance of superconducting magnet and magnetic shield is being studied to improve the Maglev system at the Kunitachi Institute. This paper describes the development of JR's Maglev system.