The Large Helical Device (LHD) is a non-tokamak type superconducting toroidal fusion apparatus. The LHD project contributes to the physics and technological developments exploring the currentless and steady-state plasmas, which have the high performance of temperature, density, confinement time and beta values being extrapolatable to the reactor condition. This paper reviews the major progress of the SC magnet technology attained from R&D programs, design and construction of LHD.