Clostridium bacteremia is a well-known cause of infection in patients with gastrointestinal lesions. However, the clinical characteristics of this infection in cancer patients are unclear. We retrospectively reviewed cases of blood cultures positive for Clostridium species between March 1, 2004 and May 30, 2018 at the Shizuoka Cancer Center Hospital. Medical records of 40 patients who met the study criteria were reviewed for age, gender, underlying disease, history of disease, blood culture results, laboratory test results, and radiographic data. The common sources of Clostridium species in these patients were hepatobiliary tract infection and liver abscess (13/40; 32.5%) and bacteremia/enteritis due to gastrointestinal tumor (13/40; 32.5%). All patients had malignancies, with the most common being colorectal cancer (n = 9) followed by pancreatic cancer (n = 8) and gastric cancer (n = 6). The most common species isolated was C. perfringens followed by C. ramnosum. Twenty-five patients (62.5%) had polymicrobial bacteremia with the following organisms isolated from concurrent blood cultures: Escherichia coli (n = 8) and Klebsiella spp. (n = 7). Of these bacteremia cases, 37 had digestive organ lesions such as gastrointestinal malignancy, peritoneal dissemination, or intestinal infiltration. Seventeen patients died, resulting in an overall mortality rate of 42.5% at 30 days. Common cases of Clostridium bacteremia were derived from gastrointestinal lesions, and because Clostridium bacteremia is observed regardless of species, it should be considered necessary to examine gastrointestinal lesions.