Recently, for the electrical devices operating at high frequency, suppression of electromagnetic radiation field at high-frequency bands is required under EMC guidelines. EMC test measurements and suppression methods for electromagnetic radiation generated at high-frequency bands are under investigation. But, discussion on the electromagnetic radiation resulting from interconnected devices is limited. So, we focus on an effect of connectors which decreases contact performance on electromagnetic radiation when devices are interconnected with each other. In previous studies, we have shown the effect of loose contact of a connector on electromagnetic radiation. These studies have shown that inductance and resistance value at a connector contact boundary are increased by loosening a connector and electromagnetic radiation is increased by changes of values of those high-frequency circuit elements. To investigate the mechanism of increase on electromagnetic radiation field by loose contact connector, we analyze the dominant element of high-frequency circuit to cause electromagnetic radiation. Moreover, to acquire contact requirements for a connector in order to suppress electromagnetic radiation, we compare the impact of inductance and resistance on electromagnetic radiation under different frequencies.