A memory system includes a memory device having a controller and a memory cell array, and a host device connected to the memory device and configured to transmit a first request for storing internal information of the memory device and a second request for acquiring internal information of the memory device. The controller, in a first control mode, writes data in the memory in response to a write request from the host device and reads data from the memory in response to a read request from the host device, in a second control mode, does not respond to write and read requests from the host device, and when receiving the first or second request, shifts from the first control mode to the second control mode, performs an operation according to the first or second request, and shifts to the first control mode without restarting or initializing the memory device.