PURPOSE: To obtain an apparatus for automatically casting a plate-like lead piece of balance wt. at high velocity.

CONSTITUTION: This apparatus provides a lower die 10 composed of a flat bottom face 11, front wall 12 and runner forming members 15 opening/closing by sliding on a sliding surface 14 and forming the runner 18 in abutting part at the time of closing, and an upper die 20 having the same width (a) as the flat bottom face 11 in the lower die 10 and forming a recessed part 23 deciding vol. of the balance wt. at the lower face and a nozzle 34 for supplying molten lead into the recessed part 23 through the formed runner 18. Further, by arranging a first detaching member 17 protruding upward from the flat bottom face 11 in the lower die 10 and a second detaching member 25 protruding downward in the recessed part 23 in the upper die, the detachment of plate-like lead piece remained in the flat bottom face 11 in the lower die 10 or the recessed part 23 in the upper die 20, is made to easy.