to the above case it is assumed that the erroneous mounting of the clock spring is carried out under the condition where the number of wrappings of each flexible cable 5 accommodated in the second cable accommodating grooves 16 of the upper case 2 is larger than that in the first cable accommodating grooves 11 of the lower case 1 in this case when the steering wheel is rotated in the counterclockwise direction shown by arrow c toward the counterclockwise terminal position the flexible cable 5a is entirely taken into the second cable accommodating grooves 16 before the steering wheel reaches the counterclockwise terminal position accordingly when the steering wheel is further rotated in the counterclockwise direction from the above condition a tension is applied to the flexible cable 5a by a torque of the steering wheel to finally cut the flexible cable 5a such a cutting operation can be easily effected because a round cable employed as each flexible cable is cut more easily than a flat cable and the flexible cable 5a only is to be cut for instance a cutter for cutting the flexible cable 5a is provided by utilizing peripheral edges of the cable leading hole of the lower case 1 and the cable leading hole 17 of the upper case 2 thereafter when the flexible cable 5a is cut this is.