A computer-implemented method for determining a manufacturing condition (C) under which a three-dimensional object is built by layering an additive manufactured material based on design data (D) 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 (D); 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 (R) 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 (D); 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 (R) 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 (R) 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. <EOS>