This study is an attempt that Rheology changes are occurred by boiling, frying, and boiling potatoes with soy bean sauce. Three different methods are tested for chemical analysis, fine potato starch grain structural change, sensory evaluation. 1) Alkaline number and acidity number are changed (+)2.17 in raw, decreased (+)1.76 by boiling, increased (+)2.38 by frying, and (-)2.22 by boiling with soy bean sauce. 2) Potatoes are completely dissolved into the gelatinization when they are boiled at 10$0^{circ}C$ for 15minutes(PB III), fried at 18$0^{circ}C$ for 3 minutes(PF IV), and boiled with soy bean sauce l0$0^{circ}C$ for 30 minutes(PS III). 3) The pectin content ratio is decreased according to frying (31.78$mu extrm{g}$/$mell$), boiling(44.20$mu extrm{g}$/$mell$), boiling soy bean sauce(36.37 $mu extrm{g}$/$mell$), Hemicellulose content ratio is decreased according to frying(1.19%), boiling(1.17%), boiling soy bean sauce(0.92%). And the contend of cellulose and lignin is still regardless of any cooking method. 4) The sensory evaluation conducted by 30 university students as panelists showed that there are more significant differences among four samples in appearance, flavour, texture. As a result, the optimum cooking condition for potatoes is that potatoes are boiled l0$0^{circ}C$ for 15minutes, fried at 18$0^{circ}C$ for 3minutes, and boiled with soy bean sauce at 1$0^{circ}C$ for 30minutes.