1. A three-dimensional map display system that displays a three-dimensional map, comprising: a drawing map database that is used to draw the three-dimensional map; and a display controller that refers to the drawing map database and displays the three-dimensional map as a bird's eye view from a viewpoint position looking down from a height and in a gaze direction, wherein the drawing map database stores: feature polygon data used to draw feature polygons representing shapes of features to be drawn in the three-dimensional map; and shading wall polygon data used to display a shading wall polygon, which is a virtual plate-like polygon to express shading in the three-dimensional map, is set perpendicular to or inclined to a feature polygon for which the plate-like polygon is to be set, and is specified to be visible only from one surface of front and rear surfaces and to be transparent from the other surface, and the display controller displays only the surface specified to be visible with respect to the shading wall polygon.