An illuminating device according to the present invention comprises a
first reflector for irradiating forward light beams from a light source,
a second reflector that has an aperture and is disposed in front of the
first reflector so as to reflect toward the light source the light beams
from the first reflector to condense the light beams, a third reflector
disposed so as to make the light beams condensed by the second reflector
exit through the aperture, and a reflector moving means that moves the
second reflector or the third reflector along an optical axis.