Quantum efficiency (QE) evolution by several negative electron affinity (NEA) activation process for p-doped GaAs(100) specimen has been studied. We have carried out the surface pretreatment at 580°C or 480°C and the successive NEA activation process at room temperature (R.T.). When the NEA surface was degraded, the surface was refreshed by above pretreatment and activation process, and approximately 0.10 of QE was repeatedly obtained. It was found that the higher QE of 0.13 was achieved with the reduced pretreatment temperature at 480°C with the specific experimental conditions. This is probably caused by the residual Cs-related compounds playing an important role of the electron emission. In addition, after the multiple pretreatment and activation sequence, surface morphology of GaAs remarkably changed.