A method of manufacturing composite yarn by doubling and twisting paper tape and back warp yarn in one process without doubling paper yarn and back warp yarn after fabricating the paper yarn using the paper tape, includes: passing paper tape unwound from a bobbin by external force through the bobbin in an axial direction of the bobbin, and rotating the paper tape together with additionally-supplied back warp yarn about the axis of the bobbin to twist the paper tape and the back warp yarn together.