POWER SOURCE DEVICE FOR VEHICLE

A vehicle power source device which can improve the accuracy of battery deterioration detection. The vehicle power source device (100) is provided with: generator (110) which is in-built in a vehicle; high-voltage first battery (120) which stores the electricity generated by the generator (110); DC/DC converter (140) which is provided between the generator (110) and the first battery (120), and electrical component (180); second battery (130) which is connected to the first battery (120) via the DC/DC converter (140), and which has a lower voltage than the first battery (120); and power source ECU (150) which controls the DC/DC converter (140). If the current drawn from the first battery (120) satisfies predicted conditions, the power source ECU (150) increases the output voltage of the DC/DC converter, measures the parameters required to detect the deterioration of the first battery (120), and determines the deterioration of the first battery (120).