A Ni-base directionally solidified alloy casting is produced by casting a Ni-base directionally solidified alloy having a composition of 10 to 14 wt.% Co, 2 to 3 wt.% Cr, 1.5 to 2.5 wt.% Mo, 5 to 6.5 wt.% W, 5.7 to 6.5 wt.% Al, 5.5 to 6.5 wt.% Ta, 4.5 to 5.0 wt.% Re, 0.01 to 1.5 wt.% Hf, 0.01 to 0.30 wt.% C, 0.01 to 0.03 wt.% B, and the balance of Ni and inevitable impurities. The Ni-base directionally solidified alloy casting is subjected to a solid solution treatment process at a temperature in the range of 1250 to 1300°C. Then the Ni-base directionally solidified alloy casting is subjected to a two-stage aging process for aging the Ni-base directionally solidified alloy casting at a temperature in the range of 750 to 1200°C.