A ladder rope retaining device includes a support base and a rotating base. The support base has a bottom wall and two opposite straight walls connected with the bottom wall. The bottom wall has two opposite elastic support portions protruding out of the bottom surface thereof. The straight walls each have a pivot trough. A positioning bump is formed at the periphery wall of one pivot trough. The rotating base includes a pivot pivotally disposed in the pivot troughs, and a ladder rope retaining portion formed on the pivot. The pivot has a plurality of positioning recesses arranged in an equally-spaced manner. When the rotating base is rotated relative to the support base, the positioning recesses are alternately engaged with and disengaged from the positioning bump to generate a better operating feel. As they are disengaged from each other, the support base becomes deformed elastically.