Ground anchor method is one of the most popular reinforcing technology for slope in Korea. For the health monitoring of slope which is reinforced by permanent anchor for a long period, monitoring of the tension force of ground anchor is very important. Optical FBG sensors embedded tendon was developed to measure the strain of 7-wire strand by embedding FBG sensor into the center king cable of 7-wire strand. This FBG sensors embedded tendon has been successfully applied to measure the reinforcing force of ground anchor during four seasons through temperature compensation of the FBG sensors embedded tendon.