To provide a batch type supercritical water reaction apparatus with which operation is easy.

This batch type supercritical water reaction apparatus 10 is an apparatus for treating hardly pulverizable organic solids by a supercritical water reaction and has a first reactor 12 of a batch type, a second reactor 14 of a continuous vessel type of a two-zone system which is connected in series to the first reactor, a water feeding means 16 which feeds supercritical water to the first reactor 12, an air compressor 18 which feeds air as an oxidizing agent to the firs and second reactors, a reaction product outflow system 20 which subjects the reaction product fluid and subcritical water drain flowing out of the second reactor 14 to separation of gas from the liquid, a subcriticl water drain outflow system 21, and a firs and a second temperature controllers 38 and 40 which control the temperatures in the first and second reactors. The first reaction product fluid containing unrecompensed matter flowing out of the first reactor 12 is subjected to the supercritical water treatment in the second reactor 14, by which the perfect supercritical water treatment of the hardly pulverizable organic solids is made possible. The suppression of the corrosiveness of the second reactor 14 by the two-zone system is made possible.