A storage device and an operating method of the storage device are provided. The storage device comprises a first non-volatile memory device, a second non-volatile memory device, a third non-volatile memory device a storage controller configured to control the first non-volatile memory device, the second non-volatile memory device, and the third non-volatile memory device, control the first non-volatile memory device to extract a first on-cell count value after a first soft erase operation, set first to third read level offsets of the respective first to third non-volatile memory devices based on the respective first to third on-cell count values, select the first to third defense code parameter sets each corresponding to the respective first to third read level offsets, and transmits first to third read commands based on the selected respective first to third defense code parameter sets to the respective first to third non-volatile memory devices.