A flat-cable guide device (1) includes first and second cable guide paths (30, 40) in which slits (S2) of rear end walls (32, 42) which respectively allow a flat cable (200) to be inserted are provided so as to be inclined at a prescribed angle (θ) to slits (S1) of front end walls (31, 41) and a third cable guide path (50) which connects the slits (S2) and (S2) in the rear end walls (32) and (42) of the two guide paths by a U-shaped guide path (53) in which the flat cable (200) can move.