PURPOSE: A memory device is provided to prevent response time delay about a request of a host by processing a valid page of a defect block in idle time. CONSTITUTION: A control unit manages a global reserved area, a first virtual area about a first memory chip, and a second virtual area about a second memory chip. The first virtual area includes a first user area and a first reserved area. The second virtual area includes a second user area and a second reserved area. The global reserved area includes first reserved blocks and second reserved blocks. If a first virtual block is detected to a bad block, the control unit allocates a second virtual block to the first user area.
