A vertical spindle duplex head for a grinder includes an annular pressure wheel and a receiver wheel arranged to rotate and revolve workpieces between the annular surfaces of the pressure wheel and the receiver wheel and a grindstone for one end portion of the workpieces driven in the opposite directions of rotation of the pressure wheel and receiver wheel and at their different rotational ratios. The workpieces rotate and revolve between these wheels, thereby grinding their end face by means of a grindstone arranged around the external periphery of a rotary carrier.The pressure wheel and receiver wheel are rotatably driven in opposite directions and at their different rotational speeds by distributing driving force from one source to each of them and a variable driving means is provided on one of the transmittance routes of the driving force extending from the place of distributing the driving force to both of the pressure wheel and the receiver wheel, whereby the rotational ratio of each of them can be optionally changed.