  The LMA solution of the solar neutrino problem has been explored with the
1,000 ton liquid scinatillator detector, KamLAND. It utilizes nuclear power
reactors distributing effectively 180km from the experimental site. Comparing
observed neutrino rate with the calculation of reactor operation histories, an
evidence for reactor neutrino disapearance has been obtained from 162 ton-year
exposure data. This deficit is only compatible with the LMA solution and the
other solutions in the two neutrino oscillation hypotheisis are excluded at
99.95% confidence level.
