An electronic apparatus input and/or output a signal from and/or an external apparatus. The electronic apparatus includes: a clock section in which a frequency is set and which gives a clock signal having the set frequency; an input-output section which inputs and/or outputs the signal according to the clock signal given from the clock section; a frequency detecting section which detects a frequency of a signal given from the external apparatus; and a frequency setting section which determines the frequency of the clock signal based on the frequency detected by the frequency detecting section, and sets the frequency in the clock section.Since the frequency of the clock signal is automatically set based on the frequency given from the external apparatus, it is possible to diminish a cumbersome maintenance work or reduce the cost.