A flat cable winding device includes: a base plate in which a central shaft for holding one end side of the flat cable is erected on the center of the upper surface; a rotation table disposed on an upper surface of the base plate and rotatably supported around the central shaft; a spiral spring for rotationally energizing the rotation table in the winding direction of the flat cable since the energizing member is interposed between the base plate and the rotation table; and a tubular wall body mounted on the base plate while the spiral spring and the rotation table are accommodated therein, wherein a rib is formed on an inner periphery wall surface of the tubular wall body for preventing the rotation table from popping out of the base plate.