This study was performed to determine the proximate analysis of Pleurouts eryngii and quality characterisitcs of pork cutlet sauce with added king oyster mushroom (Pleurotus eryngii). Pork cutlet sauce was prepared with different levels of king oyster mushroom powder (0, 1, 3, 5, and 7%) and stored for 21days at $25^{circ}C$. Antioxidant activity was significantly increased by addition of king oyster mushroom powder (p<0.001). L, a and b value ignificantly increased with the increased of king oyster mushroom powder concentration. As king oyster mushroom powder concentration increased, pH value was increased and titratable acidity (%) value was decreased. pH value and titratable acidity (%) value were stable during storage period. Viscosity value and $Brix^{circ}$ were significantly increased by addition of king oyster mushroom powder (p<0.001). The overall acceptability, sweetness and taste of the pork cutlet sauces with added 5% king oyster mushroom powder attained high scores.