PURPOSE: To improve productivity by restraining the decrease of an illuminating light quantity around an object and the dispersion of the illuminating light quantity in an illuminated area as for an extended illuminating method and device in the case of illuminating the object which spreads in a plane state by a point light source.

CONSTITUTION: This method is the extended illuminating method in which the illuminated area 2 of the object which spreads in a plane state is illuminated by a fixed single light source 3 which is positioned above the area 2. After an illuminance distribution map on the illuminated area 2 of the object by the single light source 3 is formed, a liquid crystal panel 11 is formed corresponding to the illuminance distribution map so that a transmitted light quantity may become the largest in a panel area corresponding to an area where illuminance on the illuminance distribution map is the smallest, and so that the transmitted light area in the panel area corresponding to the area where the illuminance is larger than the smallest illuminance on the illuminance distribution map may become smaller in inverse proportion to each illuminance. In a state where such a panel 11 is disposed near the object side of the single light source 3, the object is illuminated.