We observed the field of GRB 100305A (Troja et al. GCN 10470) with the optical three color (g', Rc and Ic) CCD camera attached to the Murikabushi 1m telescope of Ishigakijima Astronomical Observatory. The observation started on 2010-03-05 13:03:55 UT (~4h after the burst). We did not find any new point source in the XRT error circle (Osborne et al., GCN 10474) in all the three bands. Three sigma upper limits of the OT are listed below. We used SDSS catalog for flux calibration. T0+[day] MID-UT T-EXP[sec] g' Rc Ic ------------------------------------------------------ 0.18816 13:36:35 3300.0 >22.1 >21.6 >20.4 ------------------------------------------------------ T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]