A memory system includes a connector through which power for the memory system is to be supplied from an external device, a controller, a nonvolatile memory device, a power source circuit connected to the controller and the nonvolatile memory device by power lines through which power is supplied to the controller and the nonvolatile memory device, and a power source control circuit that receives a supply of power from the external device through the connector and supplies the power to the power control circuit. The power source control circuit is configured to detect using a divided voltage of a voltage of the power supplied thereto, that the voltage of the power supplied thereto is higher than a predetermined voltage and interrupt the power supplied to the power control circuit if the voltage of the power supplied thereto is higher than the predetermined voltage.