Elevator ropes in high-rise buildings are forcibly excited by the displacement of the building induced by wind force. An approximate solution to the forced vibration of a rope with time-varying length and having linear damping is presented here. It is assumed that the rope tension and the moving velocity are constant, and that the damping coefficient of the rope is small. Virtual sources of waves which can be assigned to reflecting waves are used for obtaining the approximate solution. Finite difference analyses of rope vibration are also performed to verify the validity of this approximate solution. The calculated results of the finite difference analyses are in fairly good agreement with the calculated results of the approximate solution. The effects of moving velocity and damping factor on the maximum rope deflection are quantitatively made clear.