  We report the results of a prototype photometric search for transiting
extrasolar planets using Subaru Suprime-Cam. Out of about 100,000 stars
monitored around the Galactic plane (l=90 degree,b=0 degree), we find that
7,700 (27,000) stars show the photometric precision below 1% (3%) for 60 second
exposures which is required to detect extrasolar planets by the transit method.
Thus Suprime-Cam has the photometric stability and accuracy required for a
transiting planet survey. During this observing run, we detected three
transiting planetary candidates (i'-band magnitude around 18.5) which exhibit a
single full transit-like light curve with a fractional depth of <5%. While
future photometric and/or spectroscopic follow-ups remain to be done, the
estimated parameters for the three systems are consistent with planetary
companions around main-sequence stars. We also found two eclipsing binary
candidates and eleven variable stars exhibiting W UMa-like light curves.
