A road map display device including a road map information memory for memorizing road map data on a two-dimensional coordinate and a detection device for detecting a present position and a travel direction of an automotive vehicle, wherein the two-dimensional coordinate of the road map data is read out from the information memory in accordance with the present position and travel direction of the vehicle detected by the detection device and displayed in the form of a plane view on a screen of a display unit. In the road map display device, trapezoid conversion parameters are determined on a basis of a conversion formula for converting the two-dimensional coordinate of the road map to a trapezoid coordinate for display of a perspective view in such a manner that an upper side of a square two-dimensional coordinate is contracted relatively to a lower side of the two-dimensional coordinate, and the road map data included in a reverse trapezoid coordinate defined by a reverse conversion formula of the conversion formula are read out from the road map information memory and introduced into a trapezoid coordinate defined by the trapezoid conversion parameters such that the road map data are displayed in the form of a perspective view on the screen of the display unit.