A laser annealing apparatus comprises a laser oscillator having a Q
switching action, one or a plurality of partially reflective mirrors for
split a laser beam emitted from the laser oscillator into a plurality of
laser beams, a plurality of optical fibers which respectively transmit
the plurality of laser beams split by the partially reflective mirrors,
and whose respective emission ends are arranged linearly in one
direction, a first optical system for synthesizing and homogenizing the
plurality of laser beams emitted from the optical fibers, and a second
optical system for focusing the laser beam emitted from the first optical
system on the work piece surface as a rectangular laser beam whose beam
shape is long in the lateral direction and short in the longitudinal
direction. As a result, laser power transmission by means of slender
optical fibers is possible even in cases in which a green laser such as
the second harmonic of an Nd:YAG laser having a Q switching action or the
like is used as a heating light source. Accordingly, a compact laser
annealing apparatus that has a high-quality working performance and does
not require a laser amplifier or high-frequency generating apparatus can
be obtained.