A media-agitation pulverizer is capable of creating a uniformized, stable helicoidal flow in a mixture of pulverizing media and a raw material slurry, thereby performing pulverization/dispersion uniformly with satisfactory energy efficiency. The media-agitation pulverizer includes a guide ring installed to radially divide a lower region of a pulverization chamber into an inner section and an annular outer section, whereby a flow of a mixture of a raw material slurry and pulverizing media is formed as a helicoidal flow including a secondary flow flowing through a circulation flow path with respect to the guide ring; and rotational-flow suppressing device is provided within the pulverization chamber and adapted to strengthen the secondary flow of the helicoidal flow, thereby stabilizing the helicoidal flow.