ELECTRONIC COMPONENT UNIT AND WIRE HARNESS

An electronic component unit applied to a wire harness includes a power supply terminal connected to a power supply that is mounted on a vehicle and is capable of supplying power at a first voltage, a circuit branch portion that is connected to the power supply terminal to branch power supplied from the power supply into a plurality of power supply systems, and a voltage converter that is provided in at least one of the plurality of power supply systems in the circuit branch portion, and converts a voltage of the power supplied from the power supply into a second voltage lower than the first voltage to output the second voltage.