Casting method

A casting method, comprising:

• pressure filling a molten metal from a lower side through a sprue into a cavity defined by an upper die and a lower die or into a cavity defined by an upper die, a lower die and a side die to solidify the molten metal;
• and
• supplying air into an air passage that is formed in the sprue to cool the sprue at the same time that the supply of the molten metal into the cavity is stopped,
• wherein the sprue consisting essentially of, by mass content, 0.15% or more and 0.35% or less of C, 0.05% or more and less than 0.20% of Si, 0.05% or more and 1.50% or less of Mn, 0.20% or more and 2.50% or less of Cr, 0.50% or more and 3.00% or less of Mo, 0.05% or more and 0.30% or less of V, 0.0002% or more and 0.0020% or less of B, 0.0005% or more and 0.0100% or less of Ca, 0.01% or more and 0.15% or less of Se, 0.01% or more and 0.15% or less of Te, 0.003% or more and 0.20% or less of Zr, and the balance Fe;
• the sprue has heat conductivity of 34 W·(m·K)−1 to 41 W·(m·K)−1 in an operating temperature of 150° C. to 550° C.;
• the heat conductivity increases as the temperature decreases;
• and
• the material of the sprue has a higher heat conductivity than a material of the lower die and a material of the side die.