In this study cable tension of existing bridges is measured by non-contact laser vibrometer, and applicability of a non-contact vibration measurement method is experimentally evaluated. Cable tension of two existing cable bridges is measured by laser vibrometer, and test results are analyzed and compared with evaluation results acquired by using accelerometer. According to the analysis results, cable tension of existing bridge can be efficiently measured by non-contact vibrometer in a relative short time. Furthermore, the non-contact vibration measurement method reveals an error of less than 5 percent, and could be efficiently applied to a tendency analysis of tension values or to a rapid measurement in construction sites.