A power supply system includes a first battery module and a second battery module. The first battery module comprises a first nonaqueous electrolyte battery comprising a negative electrode containing a carbonaceous material. The second battery module comprises a second nonaqueous electrolyte battery comprising a negative electrode and a positive electrode. The negative electrode contains a negative electrode active material that has a lithium ion absorbing potential of 0.4V (vs.Li/Li+) or more and an average particle diameter of 1 μm or less. The positive electrode contains lithium metallic oxide represented by LixCoyM1−yO2. The second battery module is chargeable in a range of 20 to 80% of charging depth so that a charging current density (A/kg) of the second nonaqueous electrolyte battery becomes higher that that of the first nonaqueous electrolyte battery.