Power converter and motor vehicle

A power converter includes a DC-DC converter circuit unit configured to step up or step down a voltage of direct current power supplied from a power supply, an inverter circuit unit configured to convert direct current power supplied from the power supply to alternating current power, and a first flow path portion and a second flow path portion through which a cooling medium flows. The first flow path portion is disposed between the DC-DC converter circuit unit and the inverter circuit unit. The second flow path portion is disposed at an opposite side of the inverter circuit unit from a side at which the first flow path portion is disposed.