In order to realize thinned armatures, a winder which winds coils at a high density while restricting coil ends within a restricted space is provided. An armature coil winder for winding coils in an armature core assembly having a plurality of slots in an outer circumference thereof comprising a winding former equipped with a fixed former which guides a coil into two slots and a movable former which restricts a position of a coil end between the slots by moving in the fixed former along both end surfaces of an armature core toward a center thereof, a former slider which shifts the movable former to a specified position, and coil shaping mechanism which is disposed at location other than that of the former slider and equipped with coil shaping blades functioning to shape the coil in the slots, thereby making it possible to wind coils at a high density by effectively utilizing winding spaces.