Copy number variation (CNV) is one of structural variation types that shows various numbers of copies in segments of the DNA. This study aimed to identify the association between copy number variation regions (CNVRs) and carcass traits in Hanwoo. We analyzed a total of 571 Hanwoo steers with the four carcass traits (marbling score (MS), backfat thickness (BF), carcass weight (CW), loineye muscle area (LMA)). PennCNV program was used to identify the CNVs and CNVRuler program was used to analyze the association between CNVRs and carcass traits. A total of 1,659 CNVRs were identified in the whole genome of Hanwoo. These 1,659 CNVRs divided into 415 Gain, 1082 Loss and 162 Gain/Loss events. A genome wide association analysis between the CNVRs and the carcass traits was performed using CNVRuler program. The number of significant CNVR at a threshold of p<1×10-4 was 2, 7, 2 and 1 loci for MS, BF, CW and LMA, respectively. We performed gene ontology (GO) analysis for the genes in the significant CNVRs using DAVID. ABCA2 and EDF1 were related to regulation of lipid metabolic process. C8G, TRAF2 and STAB2 were related to immune. CHST11 was related to developmental growth. Our results may provide an important resource for molecular breeding research in Hanwoo.