A shot processing machine comprising: a projecting device for projecting blast material onto a workpiece; a recovery mechanism (52, 54) for recovering blast material blasted by the projecting device; and an air sorting mechanism for applying an upward air current to recovered blast material and allowing the recovered blast material to fall freely, thereby separating foreign matter mixed into the recovered blast material from that recovered blast material, wherein the air sorting mechanism comprises: a freefall zone in which the upward air current is generated, and the recovered blast material is allowed to fall freely; and a supply portion, the bottom most portion of which communicates with the free fall zone through an opening portion, by which recovered blast material is supplied; whereby the opening portion is formed between a regulator plate disposed to extend in the vertical direction on the free fall zone side of the supply portion, and an inclined portion extending diagonally downward at an incline toward said regulator plate and toward the free fall zone of the supply portion; further comprising; a cabinet within which is formed a blast chamber wherein blast material is blasted, comprising a blast chamber entrance for loading workpieces into the blast chamber, and a blast chamber exit for discharging workpieces from the blast chamber; a first shot curtain machine for causing blast material to fall in a curtain shape from the top of the blast chamber entrance; a second shot curtain machine for causing blast material to fall in a curtain shape from the top of the blast chamber exit; a recovery mechanism (52, 54) for recovering blasted blast material from the blast chamber; and a distribution box for distributing blast material recovered by the recovery mechanism (52, 54) to the air sorting mechanism and the first shot curtain machine and the second shot curtain machine and wherein blast material from which foreign matter has been separated by an air sorting mechanism is supplied to the projecting device. a projecting device for projecting blast material onto a workpiece; a recovery mechanism (52, 54) for recovering blast material blasted by the projecting device; and an air sorting mechanism for applying an upward air current to recovered blast material and allowing the recovered blast material to fall freely, thereby separating foreign matter mixed into the recovered blast material from that recovered blast material, wherein the air sorting mechanism comprises: a freefall zone in which the upward air current is generated, and the recovered blast material is allowed to fall freely; and a supply portion, the bottom most portion of which communicates with the free fall zone through an opening portion, by which recovered blast material is supplied; whereby the opening portion is formed between a regulator plate disposed to extend in the vertical direction on the free fall zone side of the supply portion, and an inclined portion extending diagonally downward at an incline toward said regulator plate and toward the free fall zone of the supply portion; further comprising; a cabinet within which is formed a blast chamber wherein blast material is blasted, comprising a blast chamber entrance for loading workpieces into the blast chamber, and a blast chamber exit for discharging workpieces from the blast chamber; a first shot curtain machine for causing blast material to fall in a curtain shape from the top of the blast chamber entrance; a second shot curtain machine for causing blast material to fall in a curtain shape from the top of the blast chamber exit; a recovery mechanism (52, 54) for recovering blasted blast material from the blast chamber; and a distribution box for distributing blast material recovered by the recovery mechanism (52, 54) to the air sorting mechanism and the first shot curtain machine and the second shot curtain machine and wherein blast material from which foreign matter has been separated by an air sorting mechanism is supplied to the projecting device. a freefall zone in which the upward air current is generated, and the recovered blast material is allowed to fall freely; and a supply portion, the bottom most portion of which communicates with the free fall zone through an opening portion, by which recovered blast material is supplied; whereby the opening portion is formed between a regulator plate disposed to extend in the vertical direction on the free fall zone side of the supply portion, and an inclined portion extending diagonally downward at an incline toward said regulator plate and toward the free fall zone of the supply portion; further comprising; a cabinet within which is formed a blast chamber wherein blast material is blasted, comprising a blast chamber entrance for loading workpieces into the blast chamber, and a blast chamber exit for discharging workpieces from the blast chamber; a first shot curtain machine for causing blast material to fall in a curtain shape from the top of the blast chamber entrance; a second shot curtain machine for causing blast material to fall in a curtain shape from the top of the blast chamber exit; a recovery mechanism (52, 54) for recovering blasted blast material from the blast chamber; and a distribution box for distributing blast material recovered by the recovery mechanism (52, 54) to the air sorting mechanism and the first shot curtain machine and the second shot curtain machine and wherein blast material from which foreign matter has been separated by an air sorting mechanism is supplied to the projecting device.