PURPOSE: To provide a simple structure for fixing the bent part of a flat cable used in a contactless electric signal transmitting device to the outer circumferential surface of a cylindrical rotator to reduce the cost of the device.

CONSTITUTION: The bent part 3 of a flat cable 2 is fixed to the outer circumferential surface 1a of a rotator 1 by a housing groove 10 for the flat cable 2 and a cover 20 for blocking the housing groove 10. The housing groove 10 is formed in parallel to the axial line 1c of the rotator 1, opposed side walls 11, 12 parallel to the axial line 1c within the housing groove 10 have locking means 13, 14 for the cover 20, respectively. The cover 20 has an outer circumferential surface 25 having the same curvature radius as the outer circumferential surface 1a of the rotator 1, means 23, 24 to be locked which are engaged with the locking means 13, 14 within the housing groove 10, and a notch 21. The flat cable 2 is taken out of the housing groove 10 through the notch 21. According to such a constitution, the bent part 3 of the flat cable 2 can be easily and surely mounted on the rotator 1 at low cost.