A master device is capable of communicating with an external device. The master device is capable of installing a slave device and allowing the slave device being detached from the master device. The slave device is capable of communicating with the master device after it is detached from the master device. The master device includes a main body and a bracket connected to the main body. The main body includes a front surface and a rear surface disposed opposite to the front surface. The front surface is provided with a receiving groove. The bracket is located at a side of the front surface. The bracket is capable of being rotated to a first position and a second position relative to the main body. The bracket is received in the receiving groove when in the first position, and is rotated out of the receiving groove when in the second position.