It is necessary to increase the J_c values when developing practical MgB₂ superconducting wire. High J_c values even in high magnetic fields were achieved using nanometer-sized Mg powder. The highly pure nanometer-sized Mg powder was fabricated using the thermal plasma method. In addition, doping with a small amount of SiC was tried for the purpose of enhancing J_c properties. The MgB₂ superconducting wires were MgB₂/Fe tapes prepared from a mixture of nanometer-sized Mg, commercial amorphous B and SiC, which were fabricated using the in-situ PIT method. The J_c values of the non-doped and 10 at% SiC-doped tapes reached 90 and 250 A/mm² at 4.2 K and 10 T, respectively. In regard to the temperature dependence of J_c, it reached at 160 A/mm² at 20 K and 4 T which nears the practical application level.