Plasma doping is performed by exposing a support substrate 11 made of a semiconductor to a plasma generated from a mixed gas of boron 51 which is an impurity and hydrogen 52 and helium 53 which are diluents so as to implant the boron 51 into the support substrate 11. Then, a preliminary heating step is performed by heating the support substrate 11 so that doses of the hydrogen 52 and the helium 53 are smaller than that of the boron 51 in the support substrate 11 by utilizing a difference between a thermal diffusion coefficient of the boron 51 in the support substrate 11 and those of the hydrogen 52 and the helium 53. Then, a laser heating step is performed for electrically activating the boron 51 implanted into the support substrate 11 using a laser.