An exposure apparatus of an optical disk master having a laser source, a
deflector for deflecting a recording laser beam obtained based on the
laser beam of the laser source and an objective lens for focusing the
recording laser beam on an optical disk master, has a lens system
provided between the laser source and the deflector, which has a first
lens for focusing the laser beam and a second lens for adjusting the
focused laser beam to a desired beam diameter; and a pinhole placed at a
practical focal position of the lens system.