To provide a casting apparatus for manufacturing a Cu-Ga alloy slab made of Cu-Ga alloy by melting and casting, which can manufacture a large-sized Cu-Ga alloy slab while sufficiently suppressing cracking.

A casting apparatus 100 includes a storage tank 3 between a crucible 1 and a mold 2. The storage tank 3 is arranged below the crucible 1, and temporarily stores molten metal tapped from a tap hole 12 of the crucible 1. The storage tank 3 has an inflow hole 32 into which the molten metal tapped from the tap hole 12 of the crucible 1 flows and a discharge hole 33 which is provided below the inflow hole 32, and can discharge the molten metal, flowing in from the inflow hole 32 and stored, by overflowing. Then molten metal flowing in from a pouring hole 22 and poured in the mold 2 has a pouring amount of 17.0-26.5 kg/min per unit time.