A barrel-shaped threaded grinding wheel for gear grinding which grinds a machining-target internal gear (W2) by rotating in mesh with the machining-target internal gear (W2), wherein the threaded grinding wheel comprises: finish threaded grinding wheels which are formed so as to gradually decrease in diameter from one end in a grinding-wheel width direction toward the other end in the grinding-wheel width direction, and in which ridges are provided at each outer periphery of the finish threaded grinding wheels in helical patterns over the entire length of the finish threaded grinding wheels in the grinding-wheel width direction and finish grinding surfaces are formed at left and right inclined faces of each ridge ; and characterized in that the threaded grinding wheel comprises: a super-finish threaded grinding wheel which is formed so as to gradually decrease in diameter from the center in the grinding-wheel width direction toward either end in the grinding-wheel width direction, and in which ridges are provided at an outer periphery of the super-finish threaded grinding wheel in helical patterns over the entire length of the super-finish threaded grinding wheel in the grinding-wheel width direction and super-finish grinding surfaces having higher grinding performance than the grinding performance of the finish grinding surfaces are formed at left and right inclined faces of each ridge , wherein the finish threaded grinding wheels are provided on two opposite sides in the grinding-wheel width direction, the super-finish threaded grinding wheel is provided between the finish threaded grinding wheels , and end surfaces of the finish threaded grinding wheels and end surfaces of the super-finish threaded grinding wheel are brought into contact with and coaxially connected each other so that the finish grinding surfaces of the finish threaded grinding wheels and the super-finish grinding surfaces of the super-finish threaded grinding wheel form grinding surfaces that are flush with each other in a direction of threads of the threaded grinding wheel . a super-finish threaded grinding wheel which is formed so as to gradually decrease in diameter from the center in the grinding-wheel width direction toward either end in the grinding-wheel width direction, and in which ridges are provided at an outer periphery of the super-finish threaded grinding wheel in helical patterns over the entire length of the super-finish threaded grinding wheel in the grinding-wheel width direction and super-finish grinding surfaces having higher grinding performance than the grinding performance of the finish grinding surfaces are formed at left and right inclined faces of each ridge , wherein the finish threaded grinding wheels are provided on two opposite sides in the grinding-wheel width direction, the super-finish threaded grinding wheel is provided between the finish threaded grinding wheels , and end surfaces of the finish threaded grinding wheels and end surfaces of the super-finish threaded grinding wheel are brought into contact with and coaxially connected each other so that the finish grinding surfaces of the finish threaded grinding wheels and the super-finish grinding surfaces of the super-finish threaded grinding wheel form grinding surfaces that are flush with each other in a direction of threads of the threaded grinding wheel . <EOS>