The invention discloses a memory device and a relevant erasing method thereof. The memory device comprises a plurality of memory blocks and a controller, wherein the memory blocks comprise at least one first memory block and at least one second memory block. The erasing method executed by the controller comprises the following steps: carrying out a first-stage erasing operation and a second-stage erasing operation in the at least one first memory block in the memory blocks in a first period and a second period in sequence; and carrying out the first-stage erasing operation and the second-stage erasing operation on the at least one second memory block in the memory blocks in the second period and a third period in sequence.