Provided is an insole design system that can determine design parameters in accordance with set rules and can explain the design parameters in an easy-to-understand manner.The present invention is provided with: a foot dimensions input unit (52) that receives input of the dimensions of the outer shape of a foot; a design parameter input unit (54) that, with respect to the shape of a specific portion of the surface of an insole, receives the input of design parameters determined with the position of a foot bone as a baseline; a bone position estimation unit (56) that, from the dimensions received by the foot dimensions input unit (52), estimates the position of the bone that is the baseline of the design parameters; and a data calculation unit (58) that calculates data for fabricating the shape of the surface of the insole from the design parameters received by the design parameter input unit (54) and the position of the bone estimated by the bone position estimation unit (56).