The following experiments were carried out at rock method oyster field at Uduri, Dolsan-myon, Yeocheon-gun, Jeon-nam, Korea, in 1966. In this experiment, the settling rate of oyster at each exposure level and their growth rate were checked. 1. The settling rate of oyster spats was highest at 4 hour exposure level in the day-time during spring tide, and the growth rate became greater the lower ... [Show full abstract] stratum until 3 hours and 30 minutes exposure level. 2. Rocks applied at the place higher than 5 to 6 hour exposure level which amount 26 percents of applied rocks, were not utilized properly because the settling rate of spats and their growth rate were very bad. 3. For the future application of rocks for oyster culture, effort should be paid to instruct the oyster farmers to apply all rocks at proper exposure Ie el with bottom leveling and the rocks should be spaced properly for better barvest.