This study was conducted to develop a functional cookie with the addition of a sweet pumpkin powder on a cookie shape, that showed high preference level to all age group and that was very easily to store because of low moisture content, by substituting partially a sweet pumpkin powder for reducing content of wheat flour. This study has produced the sensory optimal composite recipe by making iced cookies, respectively, with each 5 level of Sweet pumpkin powder($X_{1}$), sugar($X_{2}$), butter($X_{3}$), by C.C.D(Central Composite Design) and conducting sensory evaluation and instrumental analysis by means of RSM(Response Surface Methodology). Sensory items showed very significant values in color, appearance, flavor, overall quality(p<0.05), texture(p<0.01), and instrumental analysis showed significant values in lightness, redness(p<0.01), yellowness, spread ratio, hardness(p<0.05). Also sensory optimal ratio of Sweet pumpkin cookie was calculated as sweet pumpkin powder 81.8g, sugar 116.6g, butter 210.7g, and it was revealed that the factors of influencing cookie aptitude were in order of Sweet pumpkin powder, butter, sugar.