We evaluated the learning curve for achieving expertise in robotic rectal cancer surgery based primarily on operative time and short-term outcomes. Sixty-two consecutive patients with rectal cancer underwent robot surgery (abdominoperineal excision n = 1, low anterior resection n = 50, ultra-low anterior resection n = 10, Hartmann operation n = 1). Robotic cases were grouped by consecutive 10 cases. There were 48 cases of mid and low rectal tumor (preoperative chemoradiation n = 9). Mean operative time was 390 minutes and postoperative complication rate was 12.9%. Robotic surgery for mid and low rectal tumors was commonly performed after 10 cases. The operative time and console time of robot surgery showed first decrease after 20 cases. There were no differences in postoperative complications including anastomosis leakage, lymph node count, and distal margin between the learning periods. An experienced open surgeon with limited laparoscopy experience may begin to perform robotic rectal surgery safely without a long learning period.