Utilizing East Asian GRB Follow-up Observation Network (EAFON) we have
observed 55 GRB optical afterglows and detected 15 early optical afterglow
behavior including two short GRBs in multi-bands. We have found a common
feature in long GRB early afterglow light curves. These early light curves
show re-brightening and/or plateau phase around 0.1 days (2.4hours) after
bursts. Combine with other prompt optical observations and X-ray
data, overall behavior of thesemulti-band light curves may be interpreted in terms of the sum of two
separate components, one showing a monotonic decay from prompt while the
other having a rising and a falling phase. These results imply that prompt
optical emission continue until 0.1 days and afterglow components dominate
than prompt emission around 0.1 days.