An image processing program causes a computer to execute processing of obtaining an image, photographed with a camera, of markers disposed in a real space, creating vectors from the camera and to the markers, selecting a reference marker from the markers, calculating a inner product of the vectors, canceling use of a negative sign included in an equation that obtains a distance between the camera and a remaining marker, creating sign patterns based on to the cancelled remaining markers, setting a first distance between the reference marker and the camera, calculating candidates of a distance between the camera and the remaining markers, calculating error between an inter-marker distance in a real space and the sign patterns, calculating other error when a second distance is set, determining the distance according to the error and the other error, and calculating a position and pose of the camera according to the determined distance.