1. A method for generating a mesh of an object for three-dimensional analysis, comprising: a surface-dividing step of dividing the surface of the object to be analyzed into triangles; a thickness-acquiring step of acquiring the thickness of the object at positions corresponding to the triangles; an outer-region-element-generating step of determining a distance for which each triangle is to be projected toward the inside of the object in accordance with the thickness of the object at the position corresponding to the triangle and generating a pentahedral element in an outer region of the object by projecting the triangle for the determined distance; and an inner-region-decomposing step of decomposing an inner region of the object into tetrahedral elements, wherein, in the outer-region-element-generating step, the distance for which each triangle is projected decreases as the thickness of the object at the position corresponding to the triangle decreases.