Provided is a motor driving unit (1) capable of achieving space saving of a motor room and cost reduction of a vehicle. The motor driving unit (1) includes a motor (10), an inverter (50) that controls driving of the motor (10), and a transaxle (30). The inverter (50) is disposed at a position facing the second gear (32) in the transaxle (30) in a Z-axis direction of the motor (10), and a flow channel of refrigerant arranged inside the inverter (50) is partitioned off from an internal space of the motor (10) by a single barrier.