Disclosed is a method for automatically setting ID in UART ring communication in which a master and a plurality of slaves are formed in a ring-type network, the method including initializing the master to output a master ID (initializing step), receiving, by the plurality of slaves, the master ID, setting its own IDs by adding the master ID to a reference value and outputting the set ID (slave ID setting step), changing, by the plurality of slaves, its own IDs based on whether its own ID is same as the received ID, receiving, by the master, the IDs outputted by the plurality of slaves, and changing a currently highest value of slave IDs stored in the master in response to values of received slave IDs (changing step), and finishing the ID setting or re-setting the slave IDs, in response to the Current Max Slave ID (finish determining step).