Abstract: A stereoviewer for observing a stereo pair of photographs three-dimensionally through binocular lenses is shown and described. The stereoviewer comprises a box-shaped main body case having a space for accommodating stereoscopic photographs; a lid for covering the main body case; holder portions provided on one side surface of the box-shaped main body case so as to position and hold the stereoscopic photographs in a non-perpendicular standing state; and binocular lenses provided thereon are inclined in such a manner that the binocular lenses face the vertical center portion of the stereoscopic photographs. This stereoviewer also serves as a package and has a simple structure. The thickness of the binocular lenses are varied so that the focal distance is different between the upper portion and the lower portion of said binocular lenses and the binocular lenses are decentered outwardly in the horizontal direction.