Compact Toroid (CT) injection is considered to be an advanced deep fueling method in tokamaks. We developed a CT injector to investigate the possibility of refueling and density control of tokamak plasmas by CT injection in the JFT-2M tokamak. The velocity of the CT was controllable from 120km/s to 190km/s in the case of CT density-6×10²¹m^-3 by changing the voltage of the acceleration bank. We demonstrated the CT penetration into the central region of OH plasmas at B_T=0.8T. The tokamak electron density increased-0.2×1019m^-3 at a rate of 2×10²¹m^-3/s and the fueling efficiency was about 20%. The penetration depth into the tokamak magnetic field was determined by the balance between the CT kinetic energy density and the toroidal magnetic field density.