To provide a slurry feeder forming no stagnation of abrasive grains at a corner part or a bottom part of a tank.

This slurry feeder is constituted to store slurry in cylindrical buffer tanks 20, 22, to connect feed piping 20a, 22a to the bottom part, to connect return piping 20b, 22f to the upper part and to close the upper part. A return passage tip part 50 discharges slurry into the buffer tanks 20, 22 along the internal wall of the buffer tanks 20, 22. Agitating mechanisms 54 are provided near the bottom parts in the buffer tanks 20, 22 and near connection parts of the feed piping 20a, 22a to agitate slurry. A feed pump 36 is connected to the feed piping 20a, 22a to feed slurry to the outside of the slurry feeder and forms the vortex of slurry in the buffer tanks 20, 22.