A simple method of evaluating EMI levels from module devices is proposed. This method measures a disturbance current at the power supply port and is effective to reduce evaluation costs. However, the relation between the disturbance current and the radiating electric field strength is not clear. In this paper, the relations were investigated by using a SO-DIMM, an USB memory, and the imitated equipment. The results showed that the ratio of the radiating electric field strength to the disturbance current increased in proportion to the square of frequency in the case of the SO-DIMM and the USB memory. On the other hand, the ratio changed periodically in the frequency range more than the first resonance frequency in the case of the imitated equipment. These results suggested that the radiation from the circuit of the SO-DIMM and the USB memory was larger than the radiation from the interface cable.