A 45-year-old woman was first seen by us 2 years after becoming aware of a slightly painful subcutaneous mass in her left vulva. The mass was 7.5 × 3.0 cm in size, well circumscribed, mobile, and rubbery. It was at first clinically considered to be a benign tumor. Microscopically, the resected mass was composed of spindle or polygonal tumor cells which were cellularly or hypocellularly arranged with perivascular accentuation in a mucoid or fibrocollagenous background. Immunohistochemically, myxoid tumor cells were positive for vimentin but not for α-smooth muscle actin, CD34, CD31, desmin, or S-100 protein. The tumor was diagnosed as an angiomyofibroblastoma (AMBF), based on the typical findings of histology and immunohistochemistry. There are many histological types of vulvar tumors, and establishing a preoperative diagnosis is difficult in many patients. Rapid intraoperative pathological diagnosis should be performed if possible, considering the possibility of diseases such as AMFB and aggressive angiomyxoma (AAM). When AAM is suspected, the peripheral tissues should also be resected to prevent recurrence.