A data storage device including a main body and a storage element is provided. The main body has a first connecting part and a second connecting part, suitable for being connected to a first electronic device and a second electronic device, respectively. The storage element is disposed at the main body and is electrically connected to the first connecting part and the second connecting part, wherein the data storage device is suitable for receiving data from the first electronic device, and the data is stored in the storage element, or is transmitted to the second electronic device, or the data is stored in the storage element and is transmitted to the second electronic device. In addition, an operating method of the data storage device is also provided.