PURPOSE: To efficiently recover oil and heat, by introducing part of a cooling gas which has a recovered sensible heat from oil shale ash by cooling the ash after treatment of residual carbon into a residual carbon treating zone and burning the residual carbon in the oil shale with the gas.

CONSTITUTION: Oil shale charged to a shaft kiln is introduced through a preheating zone, a dry distillation zone and a calcination zone at 600W1,100°C into a cooling zone at 700W800°C, into which a cooling gas is introduced, and heat sustained in an oil shale ash is recovered by cooling the ash after treatment of residual ash with the gas to obtain a gas at 600W700°C. Then the gas is withdrawn out of the system and partially raised to the calcination zone, where residual carbon in the oil shale after dry distillation is burned. The exhaust gas is withdrawn out of the system and, after combined with the heated cooling gas, subjected to heat exchange with a gas for dry distillation to be supplied to the dry distillation zone. The heated gas for dry distillation is supplied to the dry distillation zone.