We performed a safe and simple transanal tumor resection involving total layer resection using a harmonic scalpel as a resecting device. Here we report the results of our experience with this technique between 2005 and 2011. This study involved 32 patients who underwent transanal tumor resection using a harmonic scalpel. The subjects comprised 18 men and 14 women ranging in age from 34 to 87 years (mean: 64.5 years). The tumors measured 8 to 70 mm (mean: 31 mm) in diameter. The operation took 7 to 86 minutes (mean: 29 minutes), and the amount of bleeding was 0 to 165 mL (mean: 16.2 mL). There was no intraoperative blood loss that necessitated hemostatic procedures. Histopathologically, the lesions included hyperplastic polyp in 1 case, adenoma in 9, carcinoma in situ in 7, submucosal invasive cancer in 6, muscularis propria cancer in 4, carcinoid in 1, malignant lymphoma in 1, gastrointestinal stromal tumor in 1, mucosal prolapsed syndrome in 1, and mucosa-associated lymphoid tissue lymphoma in 1. With our technique, en bloc resection was achieved in all patients, and the use of a harmonic scalpel enabled us to complete the operation within 30 minutes, on average, without intraoperative bleeding.