We report the case of a 68-year-old woman with acute thrombotic thrombocytopenic purpura (TTP) that developed after pneumococcal vaccination. She was found in a confusional state with high fever 15 days after vaccination. Laboratory data showed hemolytic anemia and thrombocytopenia, and blood smear showed fragmented erythrocytes. TTP was diagnosed based on the clinical presentation, and was subsequently confirmed by the absence of ADAMTS13 activity and the presence of inhibitor against ADAMTS13 in serum. She was successfully treated using plasma exchange and corticosteroids, and no recurrence has been identified. This appears to represent the first report of TTP following pneumococcal vaccination.