A 56-year-old man who underwent a tooth extraction in the previous year presented with weakness of the right upper extremity. Brain CT and MRI scans showed subcortical hemorrhage in the left frontal lobe. His body temperature was 37.5°C. Blood examination revealed anemia, elevated levels of C-reactive protein, and a positive result for PR3-ANCA. Aggregatibacter segnis was identified in the incubated blood cultures, and transesophageal echocardiograms showed infectious growth in the anterior mitral leaflet. He was diagnosed with infectious endocarditis. After treatment with ceftriaxione, the clinical symptoms were improved. We concluded that infectious endocarditis caused cerebral hemorrhage and that the positive result for PR3-ANCA was a false positive. Infectious endocarditis can mimic ANCA-associated vasculitis. When ANCA-associated vasculitis is suspected, infectious endocarditis must be ruled out.