A rector for producing chlorine according to the present invention is a multi-tubular heat exchanger type reactor for use in producing chlorine by oxidizing hydrogen chloride with oxygen, characterized in that an interior of a reactor shell is divided in a tube-axis direction by a partition into a plurality of regions such that heat mediums individually circulate through respective ones of the divided regions; said reactor comprising a temperature control means for controlling the temperature of at least one heat medium selected from said heat mediums, the temperature control means being a cooler and/or a heater; catalysts having different catalytic activities are charged in the form of layers from inlets towards outlets of reaction tubes of the reactor, the catalysts being ruthenium oxide catalysts; and 40% or less of the whole ruthenium is in the region of the reaction tubes ranging from the reaction tube inlet to less than 50% of the reaction tube length, whereas 60% or more of the whole ruthenium is in the region of the reaction tubes ranging from 50 to 100% of the reaction tube length from the reaction tube inlet. A process for producing chlorine according to the present invention is characterized in that the process is carried out by using the above reactor, and comprises the step of supplying a hydrogen chloride-containing gas and an oxygen-containing gas into the above reactor so as to oxidize the hydrogen chloride with the oxygen at a pressure of 0.1 to 1 MPaG and a temperature of 200 to 500 °C.