A pipe bend die unit includes a bend die that comprises a clamp member and a counter pressure member, wherein the clamp member has a first groove part of half-circular cross section and a fitting recess extending in a peripheral direction by a first predetermined length on a planar surface perpendicular to a rotary axis. A fitting protrusion of the counter pressure member is positioned in the fitting recess to form a pipe-receiving groove of half-circular cross section, so that the counter pressure member and the clamp member are hingedly connected to one another about the rotary axis so as to be rotated relative to each other. The fitting recess possesses width expanding end face areas, where a clearance between opposing end faces is enlarged in a predetermined distance range including at least a radially outer end portion, from the rotary axis toward a radial outside.