A memory system includes an interface circuit configured to connect to a host device, a controller electrically connected to the interface circuit, and a nonvolatile semiconductor memory electrically connected to the controller. The controller is configured to transmit a first response in response to a power supplied from the host device via the interface circuit, upon receipt of a first command from the host device after transmitting the first response, determine a status of data stored in the nonvolatile semiconductor memory, and transmit to the host device a second response including the determined status of the data stored in the nonvolatile semiconductor memory.