According one embodiment, a memory device controlling method includes: receiving, by a first semiconductor memory, a read command transmitted from a controller; receiving, by a second semiconductor memory, a write command transmitted from the controller; reading, by the first semiconductor, data from the first semiconductor memory based on the read command, and transmitting, from the first semiconductor memory to the second semiconductor memory, the data and a control signal indicating that the data is output; and receiving, by the second semiconductor memory, the data at a timing based on the control signal transmitted from the first semiconductor memory without intermediation of the controller based on the write command and writing the received data into the second semiconductor memory.