We present results of three dimensional numerical simulations of the merger of unequal-mass binary neutron stars in full general relativity . A \Gamma -law equation of state P = ( \Gamma - 1 ) \rho \varepsilon is adopted , where P , \rho , \varepsilon , and \Gamma are the pressure , rest mass density , specific internal energy , and the adiabatic constant , respectively . We take \Gamma = 2 and the baryon rest-mass ratio Q _ { M } to be in the range 0.85 –1 . The typical grid size is ( 633 , 633 , 317 ) for ( x,y,z ) . We improve several implementations since the latest work . In the present code , the radiation reaction of gravitational waves is taken into account with a good accuracy . This fact enables us to follow the coalescence all the way from the late inspiral phase through the merger phase for which the transition is triggered by the radiation reaction . It is found that if the total rest-mass of the system is more than \sim 1.7 times of the maximum allowed rest-mass of spherical neutron stars , a black hole is formed after the merger irrespective of the mass ratios . The gravitational waveforms and outcomes in the merger of unequal-mass binaries are compared with those in equal-mass binaries . It is found that the disk mass around the so formed black holes increases with decreasing rest-mass ratios and decreases with increasing compactness of neutron stars . The merger process and the gravitational waveforms also depend strongly on the rest-mass ratios even for the range Q _ { M } = 0.85 –1 .