A video projector (1) comprises a projection lens (18) which projects an image on a screen (S), a zoom ring (19) which varies a magnification ratio of the projection lens (18), a drive wheel (32) which is partially protruded from a bottom face of a housing (2), and a plurality of gears (310, 311, 312) that constitutes a power transmission mechanism (31) between the drive wheel (32) and the zoom ring (19). When the video projector (1) is moved in an anteroposterior direction to the screen with rotating the drive wheel (32), the zoom ring (19) is turned in conjunction with the rotation of the drive wheel (32) through the power transmission mechanism (31). Since the magnification ratio of the projection lens (18) is varied with the turning of the zoom ring (19), the size of the image projected on the screen is varied without a direct operation of the zoom ring (19) by a user.