In previous paper1,2), we have studied the cooking-rate equatiosls by the hot water dipped cooking of sliced and spllerical potatoes. In this paper, we stuclied the cooking-rate equations by microwave heated cooking of potato slices. The values of the parameters in the rate equations by the temperature unsteady-state systesn were calculated by using a non-linear laera square method3). The cooking-rate equation were obtained as follows: dx/dθ = k (1-X) k = 5.09 x 10^4 exp [-9.90 x 10^3/R_g(t+273.2)] or dx/dθ = k (1-X)^2.0 (x+5.37) k = 7.78 x 10^12 cxp [-2.42 x 10^4/R_g(t+273.2)] where, x(--): cooking ratio, θ(s) : cooking time, t(℃): cooking temperature, R_g = 1.987 cal/mol・°K: gas constant. The calculated results show that the values of cooking rate for microwave heated cooking are very much higher than those for hot water dipped cooking.