A graph display device includes a display module, a graph display control module which displays a graph corresponding to an expression on the display module, a specifying module which specifies a point on a graph displayed on the display module, a setting module which sets a tangent that contacts the graph at the specified point, an area determination module which, of two areas divided by the tangent set by the setting module, determines one area opposite to the area in which the graph lies to be a display area for coordinate values, and a coordinate value display control module which displays coordinate values of the specified point in the area determined by the area determination module.