The temporal evolution of radial profiles of electron density and its fluctuations during NBI or NBI plus ICRF heating has been measured in the CHS edge plasma with a thermal neutral lithium beam probe. The large outward shift of plasma boundary is observed during the NBI heating, and when the plasma boundary does not move outwards in spite of increasing plasma pressure, the fluctuation level is found to decrease just outside the last closed flux surface. It is also shown that the edge plasma is stabilized by the ICRF in the NBI-sustained plasma and the vague edge plasma is removed at the same time, and that, once the vague plasma is removed, it cannot be produced again even if the ICRF is turned off.