The present invention relates to an operation method of an input/output (I/O) interface. The operation method of an I/O interface according to an embodiment of the present invention includes the steps of: selecting one among multiple output driver circuits based on a mode selection signal; and outputting a data signal using the selected output driver circuit. The mode selection signal is a control signal used to control an on-die termination (ODT) circuit included in the I/O interface.
