  We present a study of the nature of the blue early-type galaxies (BEGs) in
the GOODS north and south fields using the GOODS HST/ACS archival data. Using
visual inspection, we have selected 58 BEGs and 113 normal red early-type
galaxies (REGs) in the sample of 1,949 galaxies with spectroscopic redshifts.
We find that the BEGs are generally bluer, fainter, and less-massive than the
REGs, although a few BEGs are exceptionally bright and massive. The number
fraction of the BEGs to total early-type galaxies is almost constant
($\sim0.3$) at $z \le 1.1$. In addition, we find that the size of the BEGs in
given redshift bin decrease as redshift decreases. The BEGs look similar to the
REGs in the images and surface brightness profiles. However, at least 27 BEGs
show traces of tidal disturbances in their fine structures: elongated cores,
off-centered cores, asymmetric internal color distributions, tidally distorted
outer structures, collisional rings, or very nearby companions. Twenty-one BEGs
are detected in the X-ray bands and eleven of them are as luminous as
$L_{0.5-10 {\rm keV}} \ge 10^{43.5} {\rm erg~s}^{-1}$, indicating the existence
of AGNs in their centers. These results show that at least a half of the BEGs
may be descendants of mergers/interacting-galaxies and that at least a quarter
of the BEGs may be AGN-host galaxies. The BEGs may evolve into REGs, and the
size evolution of the BEGs is consistent with the galactic \emph{downsizing}
scenario.
