Numerous fall accidents have occurred in the construction industry worldwide. General countermeasures for fall prevention include the use of temporary scaffolds with guardrails, but these structures cannot always be installed along side construction objects because of obstacles, such as trees and air conditioning units. In such construction sites, the effective use of other safety measures, including safety ropes and harnesses, are needed. Another urgent security issue is the prevention of falls from ladders. This study focuses on a safety countermeasure applied during preparation works for residential roof repair, such as ascent or descent on portable ladders, ground-to-roof set up of safety ropes (lifelines), and rope removal upon conclusion of repair work. On the basis of experiments on a full-scale residential roof and a human dummy, an effective countermeasure that features the use of ladders, ropes, and safety retracting lifelines with shock absorbers was developed.