NOVELTY - First switch group (2a) has MOSFETs (P1,P2) with same conductivity, second switch group (2b) has MOSFETs (N3,N4) with same conductivity, and third switch group (2d) has MOSFETs (N1,N2) with same conductivity same as the conductivity of MOSFETs of second switch group. The first main electrode and the back gate electrode of the first MOSFET of the second switch group are connected together.    USE - For measuring terminal voltage of batteries or fuel cells used in electric vehicle or hybrid vehicle.    ADVANTAGE - Small and inexpensive, has high noise immunity, and enhances precise measurement without using any special electric power source.    DETAILED DESCRIPTION - A controller (4) turns ON and OFF the first switch group according to the ON and OFF operations of the third switch group. The first main electrodes of the MOSFETs of the first switch group are respectively connected to first and second nodes (Dn1,Dn2) of a battery (1), voltages corresponding to the voltages of the first main electrodes are applied to control electrodes of the MOSFETs, and the MOSFETs are turned ON and OFF according to the voltages of the control electrodes. A capacitor (Cn) is connected between the second main electrodes of the MOSFETs of the first switch group. The second main electrodes of the MOSFETs of the second switch group are respectively connected to the second main electrodes of the MOSFETs of the first switch group, and the MOSFETs of the second switch group are turned ON and OFF according to the signals input to the control electrodes of the MOSFETs of the second switch group. The second main electrodes of the MOSFETs of the third switch group are respectively connected to the control electrodes of the MOSFETs of the first switch group, and the MOSFETs of the third switch group are turned ON and OFF according to signals input to the control electrodes of the MOSFETs of the third switch group.    DESCRIPTION OF DRAWING(S) - The figure is the circuit diagram of the voltage measuring apparatus.    Battery (1)    First switch group (2a)    Second switch group (2b)    Third switch group (2d)    Controller (4)    Capacitor (Cn)    First and second nodes (Dn1,Dn2)    MOSFETs (N1,N2,N3,N4,P1,P2)