The electromagnetic waves from mobile phone and other electronic devices have been pointed out to give heavy influences not only on the cardiac pacemaker performance but also on the physiological activities of human. In present study, cotton vests on which sewed the woven fabrics consisting of polyester and stainless steel fibers were prepared to suppress the electromagnetic wave influence and the results of clinical tests were achieved to confirm the block of electromagnetic wave by vests wearing. 32 persons with cardiac pacemaker were tested on the influence of magnetic field to heartbeat under 2.6mT of magnetic flux density. 17 persons among 32 test persons whose beat pacing were influenced, were found to release from electromagnetic damage by wearing the vests. The electromagnetic wave influence by a mobile phone was applied for the same test group and 29 persons were almost completely out of the influence on the pacing. Especially, 3 persons were removed effectively from "Oversensing" of electromagnetic wave by wearing the vests. The durabilities against 50 times washing of the woven fabrics included 70% of stainless steel fiber were confirmed in regard to the electromagnetic interference shielding as well as the wearing sensations of the vests such as the softness, lightness and comfort.