Disclosed herein is a yarn plying apparatus which is able to ply two or more than two yarns, for example, a natural yarn, a synthetic yarn or a metal filament. In the present invention, the yarn packages are arranged in a radial shape at a regular interval on the base. The yarns are plied at the plying guide hole formed just above the center of the base, so the length and angles to the plying hole of the yarns moving to the plying hole are constant, whereby the constant tensile force can be maintained. Even when the thusly plied yarns are covered or twisted, the constant twisting can be obtained.