A La-140(I-pi = 3 -, T-1/2 = 40.3 h)-doped layer has been produced in CaB6 by means of radioactive isotope (RI) beam technique: Cs-140(I-pi = 1(-), T-1/2 = 63.7 s) was implanted into CaB6 and the radioactive equilibrium of Ba-140 - La-140 was achieved. The concentration of La in CaB6 was La / Ca similar to 0.001. The measured TDPAC spectra of the 2083 keV level of Ce-140 (I-pi = 4(+), T-1/2 = 3.4 ns, mu = +435 +/- 0.10 mu(N)) followed by the beta decay of La-140 showed the existence of hyperfine magnetic fields: B-hyp =-15.0 +/- 0.5 T and - 1.00 +/- 0.15 T. The present result suggests that a ferromagnetic layer was created in CaB6 by the ion implantation.