The utility model relates to an automatic machine for expansion of rice cakes. The utility model comprises a fixing frame, a power device and a bulking manufacturing device, wherein the power device and the bulking manufacturing device are fixed inside the fixing frame; the bulking manufacturing device comprises a rice bucket, a rotatable quantization device, a hopper, a rice box and a heating device, wherein the rotatable quantization device is arranged on the lower part of the rice bucket, the hopper is arranged below the quantization device, the rice box is arranged below the hopper and the heating device is parallel with the rice box. Besides, the heating device comprises a lower heating mold and an upper heating mold, wherein the lower heating mold is fixed on the fixing frame, and the lower heating mould is movably arranged above the lower heating mold; the bottom surface of the upper heating mould is convex, the top surface of the lower heating mold is concave, the lower heating mold is in convex-concave cooperation with the upper heating mould, and the upper heating mold and the lower heating mold are respectively provided with a thermometer; an output shaft of a speed reducer is coaxially provided with a speed reducer speed reducing wheel, a small chain wheel, a large elliptical cam and a small elliptical cam, wherein the small chain wheel is connected with a quantitation device wheel through a chain, the small elliptical cam is connected with the rice box through a connecting rod and a connecting rod vertical shaft, the rice box is arranged on the lower part of the rice box and the large elliptical cam is connected with the upper heating mold through a lever.