To provide a graph display device easy in comprehension of continuity of a graph made to be a display target and in tracing of a data point of the graph.

When the graph G2 has data points outside a graph display area RE1, an arrow AR indicating its presence direction is fitted to an arrow display area RE2 provided around the graph display area RE1 and is made to be displayed. Additionally, such the arrow AR is made to allow selective input by a mouse or the like, and a graph coordinate range is updated such that a nearest data point indicated by the arrow newly becomes the center of a display range when one of the arrows AR is selected by a click or the like.