A map image generation apparatus acquires material specification information representing a material specification of a material and physical property information representing a physical property of a product. The map image generation apparatus generates a self-organizing map by using the physical property information. A position in a map space, and a physical property vector indicating, for each of a plurality of types of physical properties of the product, a value related to a physical property quantity of the physical property are assigned to each of nodes on the self-organizing map. The map image generation apparatus assigns, by using the material specification information, a specification vector indicating a value related to the material specification to each of the nodes. The map image generation apparatus generates a map image in which the nodes are clustered or colored based on the specification vectors.