A differential gear mechanism (G) for driving a detaching roller of a comber is driven by two driving systems (D₁ , D₂); a driving system (D₁) which converts a constant-speed rotation motion (R) of a drive transmitted thereto into a variable-speed rotation motion through a crank mechanism (C₁) and a quadric crank mechanism (L) and transmits the variable-speed rotation motion to the input shaft of the differential mechanism (G); and a driving system (D₂) which converts the constant-speed rotation motion of the drive transmitted thereto into a swing motion by a crank mechanism (C₂), converts the swing motion into a reciprocating motion by connecting rods and linkage, and transmits the reciprocating motion to the planet pinion of the differential gear mechanism. A feed motion curve of the detaching roller given with the differential gear mechanism is an ideal curve such as that obtained by an ideally designed cam comber.