In most surgical training systems, task completion time and error ratio are common metrics of surgical skill. To avoid applying unnecessary and injurious force to the tissue, surgeons must know for themselves how much force they are exerting as they handle surgical tools. Our goal is to develop an endoscopic sinus surgery (ESS) training system that quantitatively evaluates the trainee’s surgical skills. In this paper, we present an ESS training system with force sensors for surgical skill evaluation. Our experiment revealed that the integral of the force data can also be one of the useful metrics of surgical skill.