  Using a large sample of 26623 quasars with redshifts in the range $1.5 \le
z\le 5.1$ with \civ $\lambda$1549 \AA emission line in Fifth Data Release of
the Sloan Digital Sky Survey (SDSS), we investigate the cosmological evolution
of the Baldwin Effect, i.e. the relation between the equivalent width (EW) of
the \civ emission line and continuum luminosity. We confirm the earlier result
that there exists a strong correlation between the \civ EW and the continuum
luminosity, and we find that, up to $z\approx 5$, the slope of the Baldwin
Effect seems to have no effect of cosmological evolution. A sub-sample of 13960
quasars with broad \civ $\lambda$1549 \AA emission line from SDSS is used to
explore the origin of the Baldwin Effect. We find that \civ EW have a strong
correlation with the mass of supermassive black hole (SMBH), and a weak
correlation with the Eddington ratio, $\lb/\ledd$. This suggests that the SMBH
mass is probably the primary drive for the Baldwin Effect.
