A computer-implemented method for determining a manufacturing condition under which a three-dimensional object is built by layering an additive manufactured material based on design data of the three-dimensional object, the method comprising: a specific part identification step of identifying a specific part included as a part in the three-dimensional object, based on the design data; a normal part manufacturing condition determination step of determining a normal manufacturing condition (Cn) for building a normal part other than the specific part of the three-dimensional object; and a specific part manufacturing condition determination step of determining whether to apply a specific manufacturing condition (Cs) different from the normal manufacturing condition (Cn) to the specific part and selecting the normal manufacturing condition (Cn) or the specific manufacturing condition (Cs) as a manufacturing condition of the specific part, wherein the specific part manufacturing condition determination step includes: a factor value prediction step of predicting a value of a fatigue life reduction factor which is at least one of internal defect dimension (a) or surface roughness caused when the specific part is built under the normal manufacturing condition (Cn); and an applied condition determination step of determining whether to apply the specific manufacturing condition (Cs) to building the specific part, based on a prediction result of the value of the fatigue life reduction factor in the factor value prediction step. a specific part identification step of identifying a specific part included as a part in the three-dimensional object, based on the design data; a normal part manufacturing condition determination step of determining a normal manufacturing condition (Cn) for building a normal part other than the specific part of the three-dimensional object; and a specific part manufacturing condition determination step of determining whether to apply a specific manufacturing condition (Cs) different from the normal manufacturing condition (Cn) to the specific part and selecting the normal manufacturing condition (Cn) or the specific manufacturing condition (Cs) as a manufacturing condition of the specific part, wherein the specific part manufacturing condition determination step includes: a factor value prediction step of predicting a value of a fatigue life reduction factor which is at least one of internal defect dimension (a) or surface roughness caused when the specific part is built under the normal manufacturing condition (Cn); and an applied condition determination step of determining whether to apply the specific manufacturing condition (Cs) to building the specific part, based on a prediction result of the value of the fatigue life reduction factor in the factor value prediction step. a factor value prediction step of predicting a value of a fatigue life reduction factor which is at least one of internal defect dimension (a) or surface roughness caused when the specific part is built under the normal manufacturing condition (Cn); and an applied condition determination step of determining whether to apply the specific manufacturing condition (Cs) to building the specific part, based on a prediction result of the value of the fatigue life reduction factor in the factor value prediction step.