To provide a batch-type digestion apparatus capable of homogeneously digesting the whole amount of a sample even by a low liquor ratio, allowing a digestion liquor to be added or extracted under operation at any time, enabling a digestion test corresponding to the continuous type digestion process carried out in an industrial scale to be carried out in a small scale.

The digestion apparatus is mainly constituted of a pressurizable overcoat container (1) having a supply port (13) and a discharge port (14) of the digestion liquor, and further having a heating means installed in the outer periphery part, and a sample container (2) formed into a cylindrical shape, and supported in the interior of the overcoat container (1) so that the axis may be nearly horizontal and so as to be rotatable. The sample container (2) has a structure having many holes of sizes not allowing the sample to pass through.