According to one embodiment, a memory system includes a volatile memory, a power supply circuit, and a controller. The power supply circuit includes a first power supply path in which power supplied from a host device is supplied to the volatile memory, a second power supply path in which the power is supplied from the internal power supply to the volatile memory, and a switching device that switches between the first power supply path and the second power supply path. In response to an instruction for a transition to a low power consumption mode received from the host device, the controller outputs, to the switching device, an instruction to switch the power supply circuit from the first power supply path to the second power supply path.