Carcass weight (CW) is one of the most important economic traits in pigs, directly affecting the income of farmers. In this study, a genome wide association study was performed to detect significant single nucleotide polymorphisms (SNPs) affecting CW in pigs derived from a $F_2$ intercross between Landrace and Korean native pig (KNP). Using high-density porcine SNP chips, highly significant SNPs were identified on SSC12. Two candidate genes, LOC100523510 and LOC100621652, were subsequently selected within this region and further investigated. Within these candidate genes, five SNPs were identified and genotyped using the VeraCode GoldenGate assay. The results revealed that one SNP in the LOC100621652 gene and four SNPs in the LOC100523510 gene are highly associated with CW. These SNP markers can thus have significant applications for improving CW in KNP. However, the functions of these candidate genes are not fully understood and require further study.