<p>Measuring devices (21a) and (21b) are configured as USB devices. An agent program for quality measurement is automatically activated in the measuring devices and all processings including a network setting is automatically executed by inserting the measuring devices into USB ports of relay devices located at both ends of a section to be measured. This makes it possible to easily install a measuring device, providing contribution to improvement in the line quality of a network using the result of quality measurement.</p>
