A liquid crystal display device of an embodiment has: a semiconductor laser diode emitting a first laser beam; a first reflecting unit configured to reflect the first laser beam and form a second laser beam having a one-dimensionally spread distribution; and a second reflecting unit configured to reflect the second laser beam and form a third laser beam having a two-dimensionally spread distribution. The device also has: an optical switch using liquid crystal, the optical switch being configured to control passage and blocking of the third laser beam; and a first scattering unit scattering the third laser beam.