  We have studied magnetism in anatase Ti$_{1-x}$Co$_x$O$_{2-\delta}$ ({\it x}
= 0.05) thin films with various electron carrier densities, by soft x-ray
magnetic circular dichroism (XMCD) measurements at the Co $L_{2,3}$ absorption
edges. For electrically conducting samples, the magnetic moment estimated by
XMCD was $<$ 0.3 $\mu_B$/Co using the surface-sensitive total electron yield
(TEY) mode, while it was 0.3-2.4 $\mu_B$/Co using the bulk-sensitive total
fluorescence yield (TFY) mode. The latter value is in the same range as the
saturation magnetization 0.6-2.1 $\mu_B$/Co deduced by SQUID measurement. The
magnetization and the XMCD intensity increased with carrier density, consistent
with the carrier-induced origin of the ferromagnetism.
