A binding device includes binding rod portions, coupling portions for coupling a plurality of the binding rod portions, and an axis portion serving as a center upon opening/closing of binding rods. The coupling portions have lower portions to which the axis portion is provided at a position close to base portions of the binding rods so that a leaf bound at the binding rod portions can be flipped along the binding rods and flipped through 360 degrees and leaves can make contact with each other with the axis portion sandwiched therebetween. The axis portion includes a shaft portion and receiving portions for the shaft portion. The receiving portions are provided to the coupling portions the shaft portion is disposed therein.