Provided is a dialysate supply device and a blood dialyzing apparatus including the same. The dialysate supply device includes a flow controller controlling a dialysate flow, a supply pump supplying dialysate to a hemodialyzer, a recovery pump discharging dialysate from the hemodialyzer, a volume chamber storing dialysate, and a pressure-relief bypass maintaining dialysate pressure within a permissible range. The blood dialyzing apparatus includes the dialysate supply device, a blood tube, and a one-way valve disposed on the blood tube. The blood dialyzing apparatus can quickly change dialysate pressure in the hemodialyzer using the dialysate supply device having the flow controller, cylinder and piston, and increase mass transfer and hemodialysis efficiency. Also, the blood dialyzing apparatus may be miniaturized and lightened to provide a portable blood dialyzing apparatus because blood is transferred without using a blood pump.
