To provide a rotary carbonizing system utilizable as a low-temperature carbonizing system suppressing volatile emissions, and capable of producing a high-quality carbonized product of a high carbon content and a low tar content.

The rotary carbonizing system works as follows: a dry-treated product is charged into a rotatable rotary shell oven apparatus 3 and sprayed with superheated steam while shaking the dry-treated product in the apparatus 3 to effect carbonization, wherein the superheated steam is ensured to set the average temperature difference to be large in the apparatus 3 ranging from low temperature to high temperature. Exhaust gas from the apparatus 3 is brought into a cyclone duct collector 5, and the resultant exhaust gas after collecting the majority of dust is refluxed via a dry distillation gas combustion oven 7 into a superheated steam generator 9 for spraying superheated gas on the dry-treated product. Heat released from the exhaust gas in the superheated steam generator 9 is recovered by a heat exchanger 11 and utilized as drying heat source for carbonizing pretreatment.