To provide a heat-resistant ceramic core which has complicated three-dimensional shape, can be used as a ceramic core for heat-resistant alloy and is excellent in the heat resistance, and to provide a method for producing a cast product using the core.

The production method for heat-resistant ceramic core having three-dimensional shape, is used for casting a hollow flowing passage in the inner part with a precision casting method. This method includes a powder laminate molding step for forming the ceramic core 2 having three-dimensional shape from the ceramic powder 1 coated with resin by a powder laminate molding method, an impregnating step for impregnating ceramic strengthening liquid 3 into the formed ceramic core 2 and a firing step for firing the ceramic core 2 after impregnating and strengthening the heat resistant property of the core.