PURPOSE: To obtain a level shift circuit which excels in the noise resistance characteristic and ensures an exact and stable operation with a high input impedance without adding any external parts and special proces.

CONSTITUTION: A source follower circuit 2 consists of a MOSFET which receives an input of an input analog signal through its gate and a load resistance connected to the source terminal of the MOSFET. An analog ground potential or the voltage obtained by operating the ground potential is applied to the circuit 2 as the reference voltage via the load resistance. At the same time, a MOSFET having the same conduction type and the same size as the MOSFET of the circuit 2 is applied as a load resistance and a short circuit is caused between the gate and the drain of the MOSFET. Then the floating wells are used as the back gates for both MOSFETs and the connection is secured between both wells so as to secure the same level of potential between these wells and the source of each MOSFET.