The Telescope Array (TA) experiment consists of three fluorescence
telescope stations and an array of about 500 plastic scintillator
surface detectors to explore the origin of the highest energy cosmic
rays. The construction of the TA has completed in 2007. All three
fluorescence telescope stations are fully operational since November,
2007. The surface detector array was tuned and will be fully
operational in March, 2008. The TA experiment has three big advantages
to determine the energy of the highest energy cosmic rays: plastic
scintillator detectors, HiRes telescopes, and an electron LINAC at the
site. The contradiction of the energy spectrum around the highest
energy cosmic rays originated from the difference between AGASA and
HiRes results. TA uses plastic scintillators like AGASA, which are
less sensitive to hadron interaction models and composition than the
water tanks that AUGER uses. Thus the surface detector array can
detemine energy scale independently of fluorescence telescopes. A part
of the HiRes telescopes were moved to one of three fluorescence
telescope stations of TA. Thus the HiRes telescope system and the new
TA telescope system can be crosschecked each other. We constructed a
compact electron beam LINAC in Japan. It will be installed at the TA
site for absolute end-to-end calibration of the fulorescence
telescopes by using air showers induced by electron beams with known
total energy.