A mill includes a grinding chamber, a rotating shaft located in the grinding chamber, a rotating body structured to have a rotary member fixed to the rotating shaft, a casing provided to form an outer shell of the grinding chamber, an inlet arranged to supply a solid-gas two-phase flow K containing particles and a gas to the grinding chamber, and an outlet arranged to discharge the solid-gas two-phase flow K′ from the grinding chamber. A cylindrical frame member having an inner peripheral surface formed in a corrugated shape is located in the casing. The solid-gas two-phase flow K supplied via the inlet into the grinding chamber is circled in the grinding chamber, while being accelerated by the rotating body.