In a feed block, a main conduit and sub conduits are formed. High-viscosity dope flows through the main conduit, and low-viscosity dope flows through the sub conduits. Distribution pins are disposed in a joint portion where the sub conduits intersect with the main conduit for controlling the flow volume of the low-viscosity dope. A tapered cutout is formed in the peripheral surface of the distribution pin. The distribution pin is attached in such an orientation that a wider side of the cutout coincides with the lower reaches of a dope flow. Since ledges are formed in both ends of the cutout, the amount of the low-viscosity dope flowing through the cutout is smaller in both widthwise ends than in the middle.