1. A map creation device comprising: a ground-information memory unit that stores a ground object expressing a three-dimensional shape of a ground; a simple-ground-information creating unit that creates, based on the ground object, a simple ground object expressing the three-dimensional shape with less amount of data than the ground object; an on-ground-structure-information creating unit that creates, based on the simple ground object, an on-ground-structure object expressing a three-dimensional shape of an on-ground structure that is present on a surface of the ground by adding height information to a two-dimensional on-ground-structure object expressing a two-dimensional shape of the on-ground structure; and a map-information creating unit that creates map information in which the on-ground-structure object is superimposed on the ground object.