To provide the bearing device of a stirrer for a sludge digester which efficiently prevents overheating the lower part of the bearing in the stirrer of the digester.

This bearing device of the stirrer for the digester is provided with a support disk 19 which is disposed on the apex 2 of the sludge digester 1, an upper bearing boxy 17 and an lower bearing box 18 which are fixed on the support disk 19 and a stirring shaft 13 which is supported by upper bearings 15 in the upper bearing box 17 and lower bearings 16 in the lower bearing box 18. In addition, this bearing device is provided with a cooling fan 22 for the lower bearings which is attached to the stirring shaft 13 in the support disk 19, a suction pipe 23 and a discharge pipe 24 which links the inside and outside of the support disk 19 and a cooling mechanism 20 which surrounds the circumference of the stirring shaft 13 and the cooling fan 22 for the lower bearings and is linked with the pipe end of the suction pipe 23.