Scanning Nonlinear Dielectric Microscopy (SNDM) is the first successful purely electrical method for observing ferroelectric domains. Now its resolution has become to the sub-nanometer order. In this paper fundamental study on applying SNDM system to the ferroelectric reading and writing system is performed. At first, to check the performance of the SNDM system as a ferroelectric recording system, we conduct a fundamental study on the writing of domain inversion dot in PZT thin film and succeed to have a very small domain dots with the size of 25nm. Next, we form small inverted domain dots in stoichiometric LiTaO3 single crystal for the purpose of a basic investigation of domain dynamics in a very small area. The relationship between the voltage for domain reversal and the inverted area and the relationship between the inverted domain area and the voltage application time are obtained.