Purpose: Mastectomy is one of the operative procedures of female to male transsexuals. It is aimed to excise all of breast tissues and to reconstruct male chest wall, areola, and nipple. Breast sizes are varied by developmental status and their hormonal therapy. There are several approaches for mastectomy. This study is aimed to suggest appropriate mastectomy methods according to breast size in the female to male transgenders. Methods: We retrospectively analysed 46 patients of female to male transgenders. Breast size was categorized by their inner wear size. In A cup size, mastectomy was done with periareolar approach. In C cup size, inframammary fold approach subcutaneous mastectomy was performed. In B cup size, periareolar approach was used for grade A or B ptosis patient, and inframammary fold approach was choosen for the patient with grade C ptosis. Results: Subcutaneous mastectomy was done through semicircular periareolar approach for 26 patients. There were 2 cases of major complications that should be corrected by hematoma evacuation. Circumareolar approach was used for 5 patients, and a case of nipple-areolar complex necrosis was observed. Two cases of another complications which were irregularity of breast and wound disruption could be corrected. Inframammary fold approach was selected for 15 patients. There was a case of wound disruption, so revision surgery whould be done. Four cases of breast irregularity was corrected spontaneously, and 2 cases of partial necrosis of nipple-areolar complex were corrected with secondary healing. Patient satisfaction score for periareolar, cicumareolar, and inframmammary fold approach were 4.5, 4.2 and 4.1, respectively. Some major and minor complications were observed, but satisfactory results could be secured. Conclusion: Semicircular periareolar incision looked adequate for A cup size patient, circumareolar incision was suitable for B cup size with grade A or B ptosis. In B cup size with grade C ptosis patient and C cup patients, inframammary fold incision looked suitable for optimal results.