A power supply device for a vehicle, comprising: a battery unit ( BU ), which includes a first power storage device ( B1 ); a second power storage device ( B2 ); and a selection switch ( RY0 ), a vehicle load which includes at least a first inverter driving a first rotating electric machine ( MG2 ); and a control device which makes a current flowing through said selection switch ( RY0 ) smaller than a prescribed value, which prevents the life of the selection switch ( RY0 ) being shortened, by using said first inverter to control electric power generated in said first rotating electric machine ( MG2 ) and switches said selection switch ( RY0 ), when the current flowing through said selection switch ( RY0 ) is larger than said prescribed value, wherein said selection switch ( RY0 ) selects one of said first and second power storage devices ( B1, B2 ) and connects the selected power storage device ( B1, B2 ) to said vehicle load; characterized in that said vehicle load includes: said first rotating electric machine ( MG2 ); a second rotating electric machine ( MG1 ); and a second inverter provided to correspond to said second rotating electric machine ( MG1 ), and when said control device switches said selection switch ( RY0 ), said control device controls said first and second inverters to achieve a balance between the electric power generated in said first rotating electric machine ( MG2 ) and electric power consumed in said second rotating electric machine ( MG1 ) whereby the electric power consumed in said second rotating electric machine ( MG1 ) is temporarily increased to decrease a current flowing into said battery unit ( BU ). a battery unit ( BU ), which includes a first power storage device ( B1 ); a second power storage device ( B2 ); and a selection switch ( RY0 ), a vehicle load which includes at least a first inverter driving a first rotating electric machine ( MG2 ); and a control device which makes a current flowing through said selection switch ( RY0 ) smaller than a prescribed value, which prevents the life of the selection switch ( RY0 ) being shortened, by using said first inverter to control electric power generated in said first rotating electric machine ( MG2 ) and switches said selection switch ( RY0 ), when the current flowing through said selection switch ( RY0 ) is larger than said prescribed value, wherein said selection switch ( RY0 ) selects one of said first and second power storage devices ( B1, B2 ) and connects the selected power storage device ( B1, B2 ) to said vehicle load; characterized in that said vehicle load includes: said first rotating electric machine ( MG2 ); a second rotating electric machine ( MG1 ); and a second inverter provided to correspond to said second rotating electric machine ( MG1 ), and said first rotating electric machine ( MG2 ); a second rotating electric machine ( MG1 ); and a second inverter provided to correspond to said second rotating electric machine ( MG1 ), and when said control device switches said selection switch ( RY0 ), said control device controls said first and second inverters to achieve a balance between the electric power generated in said first rotating electric machine ( MG2 ) and electric power consumed in said second rotating electric machine ( MG1 ) whereby the electric power consumed in said second rotating electric machine ( MG1 ) is temporarily increased to decrease a current flowing into said battery unit ( BU ). <EOS>