A movement detection device, intended particularly for a computer mouse or a hand-held scanner, includes a light source (7) associated with a prism (8) having a non-uniformly plane reflective face. One thus obtains an as uniform as possible illumination of the field (4) of the object whose movements will be detected. An optical system (9) inserted between the field and the optoelectronic sensor (13) fixed to a printed circuit board (6) is mounted on a support (12) fixed to the board.