Due to the complexity and difficulty of observing debris flow in the field, computational modeling has been used to investigate this geological phenomenon. One of the computational simulators for this purpose is Kanako-2D. In order to understand the phenomenon itself and the model, the present study performs a sensitivity analysis of the Kanako-2D simulator in relation to runout distance, reached area, and flow width. The values of the input parameters were individually changed in a physical-based criterion while the others were kept at standard values. Real slope-site with a history of debris flow and a hypothetical slope-site with similar characteristics were utilized. The sensitivity analysis was quantified from three methods : screening, regionalized, and variance analysis. The results show high sensitivity to Kanako-2D for the angle of internal friction, sediment diameter, the mass density of the fluid phase, and the mass density of bed material.