EAS (electronic article surveillance) systems have increased rapidly for article surveillance. In this paper, the strength of the EMF (electromagnetic fields) of EAS systems were measured. Pacemaker and ICD were investigated for inappropriate response resulting from EM (electromagnetic) EAS systems. The strength of EMF and the response of pacemaker and ICD were measured in the inner left side, outer right sides and the center of gates of the 6.3 ㎑ and 14.25 ㎑ EAS systems at a height of 130cm. As the result, EMF of the EAS system using 14.25 ㎑ was stronger than that of 6.3 ㎑. All interferences were observed only for 14.25 ㎑, and the noisy ECG was found in three static positions on the pacemaker. The ICD resulted in noise reversion and VF (ventricular fibrillation) both static and moving positions by the EMF of 14.25 ㎑ EAS system. Therefore, it is necessary to post a message warning radiation of EMF from every EAS systems and possible risk of pacemakers and ICDs.