an object of the present invention is to provide a sponge cake that does not become concave - shaped in the center even when it uses a fructooligosaccharide having physiological functions , such as decay resistance , the effect of promoting bifidobacterium growth , the effect of improving the metabolism of lipids such as cholesterol , the effect of regulating immunity , and the effect of inhibiting a rise in blood sugar level . according to the present invention , there is provided a sponge cake comprising a saccharide comprising a fructooligosaccharide , and a water - soluble polymer selected from the group consisting of collagen peptide , xanthan gum , and guar gum .