We extracted time constants capture and emission of Random Telegraph Noise (RTN), and their dependencies of the gate-source voltage from numerous MOSFETs and discuss the trapping and detrapping processes of carriers at the subthreshold voltage region. The dependence of time to capture on gate-source voltage cannot be determined by the trap depth from the interface and but by the distance between the trap and the carrier to be captured and the trap energy level. On the other hand, it is considered that the dependence of time to emission is determined by the distance between the trap and the Si/SiO 2 interface and the trap energy level. It is easy to understand emission processes compared to capture processes. We observed various emission processes caused by tunneling to Si substrate side, tunneling to gate electrode side and tunneling to either Si substrate side or gate electrode side depending on gate-source voltage. Evaluating the time constants individually is indispensable to characterize the trap which causes RTN in subthreshold voltage region.