Chagas disease is a tropical disease that is prevalent in Latin America. Described herein is an autopsy case of the sudden death of a 48-year-old Brazilian man who had stayed in Japan for 7 years. The man, who had a history of Chagas disease, collapsed unexpectedly at work. Because the cause of death was unknown, forensic autopsy examination was performed. As gross findings, the heart was dilated and rounded with an increase in size and weight. The esophagus and large intestine were dilated moderately, with extensive interstitial inflammatory infiltration in the cardiac muscle, but no apparent parasite nest was observed in various tissues. On post-mortem laboratory examinations, indirect immunofluorescence antibody test indicated the presence of IgG antibody specific to Trypanosoma cruzi in the serum. Subsequent polymerase chain reaction amplification using DNA extracted from blood yielded the specific product derived from T. cruzi genomic DNA. These examinations indicate that the infection had resulted from the Tripanosoma parasite. The cause of death was judged to be chronic cardiomyopathy caused by Chagas disease. It is important for pathologists to know the possible involvement of chronic Chagas disease in sudden unexpected deaths in the current globalized society of Japan.