A mechanism for confining a flat flexible cable of an image scanner in position is provided. The flat flexible cable is electrically connected between a circuit board and a carriage and bends differentially with the movement of the carriage relative to the circuit board under a scanning platform. The mechanism includes a confining member disposed between a first portion of the flat flexible cable and the scanning platform for isolating the flat flexible cable from the scanning platform. The confining member changes states and bends differentially with the movement of the carriage relative to the circuit board under the scanning platform, and has a bending resistance greater than that of the flat flexible cable. Accordingly, the confining member is kept at least a certain clearance from the scanning platform while confining the first portion of the flat flexible cable thereunder.