Disclosed in the present specification is to provide a connecting device for cables, in which a connecting portion and a length adjusting portion for connecting the cables are provided to be separated from each other, and a cable of a seat side and the connecting portion are easily attached to and detached from each other. According to one embodiment of the disclosure disclosed herein, proposed is a connecting device for cables, connecting a first cable connected to a folding unit of a seat of a first direction side and a third cable connected to a switch portion at a second direction side opposite to the first direction, the device including: a connecting portion; and a length adjusting portion.