PURPOSE: To let a lower die descend after molding and make exchanging of dies easy by letting the upper and lower dies having undergone positioning and fixing ascend.

CONSTITUTION: The lower protruding flight 4b of the lower die 4 of the integrally combined upper and lower dies 3, 4 is inserted into the concave groove 2c of the guide rail 2 of a moving frame 1. When the lower die 4 is pulled back after the lower die 4 has passed the end 5a of a circular stopper 5, the end 5a abuts against the lower die 4 and fixes. Next, a disc 8 is turned by a clamper 10 and is inserted into the concave groove 4a of the lower die 4 to press and fix the protruding flight 4b of the lower die 4. Next, the moving frame 1 is moved upward and is stopped when the top face of the upper die 3 abuts against a stopper 22. A disc cam 19 is turned by a lever 20 to push a cam follower 16, then a guide bar 12 moves and a clamper 21 engages with the protruding flight 3b of the upper die 3 and is thereby fixed. When the dies are lowered after molding of the casting mold, the upper die 3 is held in the ascended position and the lower die 4 descends and is exchanged with the lower die of the next molding dies.