  The MgB$_2$ superconductor, discovered in 2001, has provided unique compound
features of magnesium diboride with much higher critical temperature and
critical field compared to NbTi superconductor. Its applications have been
expanding owing to its superior energy balance in high-temperature operation
and to its excellent stability and operational margin because of the higher
critical temperature and heat capacity. This paper reviews the recent advances
in MgB$_2$ applications in the field of particle accelerators focusing on
superconducting power transmission (superconducting link) and superconducting
magnets, and also briefly discusses the future prospects and improvement
expected such as radiation hardness issues and cost-effective fabrication for
wider applications and industrialization.
