In a wide-angle image-generating device for obtaining a developed image by picking up a wide-angle image of about .+-.90 degrees using a reflecting mirror having a rotary-symmetrical convex shape, and performing computational processing, the contents of the developed image thus obtained are tilted by the amount commensurate with the inclination of the central rotational axis of the reflecting plane, which produces the drawback of giving a sense of discomfort to the viewer when the central rotational axis of the reflecting plane is tilted from a vertical direction within a plane perpendicular to a 0-degree direction. In the present invention, an angle sensor (12) is provided in the imaging device for picking up a wide-angle image of about .+-.90 degrees using a reflecting mirror (1), and the tilt within the plane perpendicular to the 0-degree direction is measured. The resulting value is used to perform development processing and to rotate the developed image by means of the computational processing device (11) so as to make the horizontals of the developed image and the TV monitor (13) conform to each other.