The present invention relates to an improved food waste dryer utilizing waste heat, which includes a main frame, a dryer drum with an access door, to be positioned in the main frame, and an agitator positioned in the dryer drum. The improved food waste dryer comprises: a waste heat supply unit, a heating jacket positioned on the outer surface of the dryer drum, with a hot-air inlet to receive the waste heat from the waste heat supply unit and a hot-air outlet to discharge the waste heat inside the dryer drum, and a condensation system positioned in the main frame, to remove moisture included in the interior air of the dryer drum to increase the drying efficiency of the food waste dryer utilizing waste heat.