ELECTRONIC CONTROL DEVICE, IN-VEHICLE SYSTEM, AND POWER SUPPLY CONTROL METHOD

A transient increase/decrease of power supplied to a reconfiguration circuit to be a logic circuit whose circuit configuration can be changed is reduced. An autonomous traveling control ECU has a reconfiguration circuit, a function control unit, a power supply circuit, and a power supply control unit. The reconfiguration circuit is a reconfigurable logic circuit. The function control unit determines an operation mode of the reconfiguration circuit on the basis of a mode determination signal and controls a reconfiguration of the reconfiguration circuit on the basis of a determination result. The power supply circuit supplies power to the reconfiguration circuit. The power supply control unit controls the power supply circuit. The power supply control unit controls a load current generated by the power supply circuit before a load variation of the reconfiguration circuit, on the basis of power supply control information to be information for controlling the power supply circuit.