The purpose of this study is to propose an optimal layout for the accelerator and brake pedals in sedan and SUV, and also to compare the pendant-type pedal with organ-type pedal. 12 male subjects participated in the experiment, the subjects were divided into 3 groups according to height percentile(under 50%ile, 50%ile to 75%ile, over 75%ile). Independent variables were seat height (H₃₀), X and Y coordinates of the center of accelerator and brake pedals and the x and y relative distance between two pedals. Dependent variable was subjective ratings for lower body discomfort. The response surface methodology using a central composite design was employed to develop a prediction model for lower body discomfort of each pedal. It is noticeable that the lateral position of the accelerator in all groups was not statistically significant. The optimal locations of both pedals were found to be distinct according to the percentile of subjects. X distance from accelerator to brake of both-type pedals is similar. But Y distance from accelerator to brake of organ-type is less about 2-3cm than that of pedant-type.