We report a rare case of a ruptured mycotic aneurysm (MA) of the deep femoral artery (DFA) associated with infective endocarditis (IE). A 59-year-old woman was referred to our hospital with acute IE. Six days after anti-bacterial therapy, she complained of sudden pain in her right thigh. This condition was diagnosed as a bacterial thrombus in the right DFA. Three weeks after valve replacement, she again complained of pain and swelling of her right thigh. CT angiography revealed a ruptured MA of the right DFA. Since the infection was completely controlled at that time, we only ligated the proximal right DFA to attain hemostasis and did not attempt excision of the MA. However, because signs of recurrent infection appeared to slightly increase after surgery, we completely excised the MA to prevent infection of the prosthetic valves. Thus far, there is no evidence of recurrent aneurysm formation and infection.