1. A vehicle surroundings monitoring device for producing a synthesized image showing the situation around a vehicle from images taken with a camera capturing the surroundings of the vehicle and presenting the synthesized image, the device comprising: a position computation section for computing position information and reliability of the position information, for a plurality of points in the camera images; an image variable-synthesis section for producing a first synthesized image from the camera images using the position information; an image fixed-synthesis section for producing a second synthesized image from the camera images by a predetermined method without use of the position information; and a synthesis scheme selection section for selecting either one of the first and second synthesized images according to the reliability as the synthesized image to be presented.