To mass-produce an aluminum roofing tile as a metallic roofing material with an aluminum die casting method and to stabily secure a low cost and supplying quantity for long term by using a casting die and forming it with a die casting machine.

In the die casting machine M, one set of movable die 1, (1') and fixed die 2, (2') for the aluminum roofing tile are fitted. The movable die 1, (1') is advanced by one stroke and completely pushed to the fixed die 2, (2') to put the dies in clamping condition. A fixed quantity of molten metal is supplied from a molten metal supplying hole Q arranged in a sleeve 4. Thereafter, a pressuring plunger 5 is advanced to eject the molten metal into a cavity A. The movable die 1, (1') is retracted by one stroke and both dies are opened to secure a space. The aluminum roofing tile as the product remaining in the movable die 1, (1') is ejected outside the movable die 1, (1') by ejecting mechanism of ejecting pins 6. The ejected aluminum roofing tile is carried outside the die casting machine M with a take-off robot, etc., and transferred to a trimming process.