1. A mesh number prediction method to predict a mesh number by a computer, comprising: obtaining, by the computer, a mesh length for a case in which a mesh having an arbitrary shape is created by approximating an analyzing target by a three-dimensional mesh model that includes the analyzing target in its entirety, based on data of a three-dimensional surface model of the analyzing target, to store the mesh length in a storage unit; obtaining, by the computer, a mesh number of each of parts forming the analyzing target for a case in which a mesh having an arbitrary shape is created by approximating each of the parts by a three-dimensional mesh model, based on the mesh length, to store the mesh number of each of the parts in the storage unit; and obtaining, by the computer, a predicted total mesh number of the analyzing target in its entirety, based on the mesh number of each of the parts, and a ratio of volumes that are obtained by comparing a volume of the analyzing target in its entirety and a volume of each of the parts, to store the predicted total mesh number in the storage unit.