  One of the main objectives of the LHD is to extend the plasma confinement
database for helical systems and to demonstrate such extended plasma
confinement properties to be sustained in steady state. Among the various
plasma parameter regimes, the study of confinement properties in the
collisionless regime is of particular importance. Electron cyclotron resonance
heating (ECRH) has been extensively used for these confinement studies of the
LHD plasma from the initial operation. The system optimizations including the
modification of the transmission and antenna system are performed with the
special emphasis on the local heating properties. As the result, central
electron temperature of more than 10 keV with the electron density of 0.6 x
10$^{19}$ m$^{-3}$ is achieved near the magnetic axis. The electron temperature
profile is characterized by a steep gradient similar to those of an internal
transport barrier observed in tokamaks and stellarators. 168 GHz ECRH system
demonstrated efficient heating at over the density more than 1.0 x 10$^{20}$
m$^{-3}$. CW ECRH system is successfully operated to sustain 756 s discharge.
