Both death certificates and postmortem examination certificates are used as proof of death. These certificates sometimes contain erroneous information but how frequently they do so is unknown. In particular, only a few studies have measured the accuracy of the cause and manner of death on Korea death documents. In this study, we compared the cause and manner of death on both kinds of certificates with those on autopsy reports to determine the frequency of errors, and to identify way to improve the accuracy of these certificates. In 2012, 528 autopsies were requested of out institute, and certificates were submitted in 241 of the cases. The manner of death was classified as natural, unnatural, or unknown. The cause of death in the autopsy report matched that on the death certificate in 37 of 63 cases (58.7%), and the manner of death matched in 40 of 63 cases (63.5%). The cause of death in the autopsy report matched that on the postmortem examination certificate in 62 of 178 cases (34.8%), and the manner of death matched in 74 of 178 cases (41.6%). Death certificates and postmortem examination certificates are important documents. We identified many incorrect reports of causes and manners of death on both kinds of documents, especially the postmortem death certificates. These inaccuracies are presumably due to a lack of forensic information and education, as well as lack of interest on the part of medical doctors.