EVAPORATIVE PATTERN CASTING METHOD

The present invention keeps a molding sand with which the inside of a foam pattern has been filled from floating up, and can be used to cast a cast object that has a favorable finished state. An opening 4 that allows a cavity 3 to communicate with the outside of a casting mold 1 is provided to a foam pattern 2, and a coating agent is applied to the opening 4. The coating agent that is applied to the opening 4 is regarded as a beam that has a second moment of area of I, a vertical-direction board thickness of h, and a length of L. The volume of the cavity 3 is V (mm3), the bulk density of a molding sand with which the cavity 3 is to be filled is ρs (kg/mm3), the density of a molten metal is ρm (kg/mm3), the angle of the opening 4 with respect to the vertical direction is θ, and the flexural strength of the coating agent when temperature is at a maximum during pouring is σb (MPa). The cross-sectional shape of the opening 4, the angle θ of the opening 4, and the flexural strength σb of the coating agent are selected to satisfy the following expression: σb I > V(ρm-ρs){(hL/2)sinθ-cosθ}.