This study examined oyster shells on a laboratory scale to determine whether they could be used as a replacement for limestone (PCC: precipitated calcium carbonate) as a filler in the paper production process. The optimum PCC production conditions and phase conversion rate at laboratory scale and 10 kg pilot plant scale were compared. For the phase conversion rate of CaO, 86.4% of the oyster shell and 55.6% of the limestone were converted. 80.4% of 86.4% CaO from the oyster shell and 52.0% of 55.6% CaO from the limestone were converted to Ca(OH)2. 99.6% of the oyster shell Ca(OH)2 and 100% of the limestone Ca(OH)2 were converted to PCC at laboratory scale. Meanwhile, the PCC phase conversion rate of oyster shells using the pilot plant was found to be 96.2%. To examine the potential for commercialization, PCC made of oyster shells was used in paper factories H and M for the applicable tests. As a result, the tensile strength, elongation, and internal bond strength of the product using the PCC from the oyster shells were similar to those of the product of paper factory H. However, approximately 2% reduction in bulk, 2% reduction in whiteness, and 0.3% reduction in opacity were reduced in paper factory H. For the product of paper factory M, the pH of 12.5 exceeds the KS standard, and the viscosity and residue are significantly higher than those of the product paper factory M. This study showed that the PCC phase conversion rate for oyster shells is higher than that for limestone under the conditions of PCC manufacturing at laboratory and pilot plant scales. The PCC whiteness test results of 99% for the pilot plant PCC, 97% for the lab scale PCC, and 93% for the limestone PCC illustrate that oyster shells are a useful material for manufacturing PCC. Because each process requires different physical properties and particle conditions, although the same PCC obtained from the oyster shells was used in both factories, it was applicable in paper factory H but not in paper factory M. Therefore, in order to examine applicability of the oyster shell-derived PCC for paper manufacturing processes, additional research is required on the adjustment of the physical properties standard and uniformity particle.