[Problem] To propose a design assistance device, design assistance method, and program, which are capable of predicting with good precision a material shape prior to alteration work from a three-dimensional shape model of a product using a fiber reinforced complex material. [Solution] Provided is a design assistance device which assists in the design of a product using a fiber material, said device comprising a processor which predicts the shape of a product prior to alteration work and creates a predicted shape model. The processor: creates the three-dimensional shape model of the product; separates the three-dimensional shape model into two or more fiber layers and creates curved-shape models; sets a correspondence between the curved-shape models; generates an orientation vector field within the curved-shape models; and makes the curved-shape models flat on the basis of the correspondence between the curved-shaped models and the orientation vector field within the curved-shape models, thereby predicting the shape of the product prior to the alteration work and creating the predicted shape model on the basis of the predicted shape.