A rotary compression molding machine comprising a table including die bores penetrating the table and an upper punch and a lower punch slidably retained above and below each of the die bores, and configured to horizontally rotate the table and the punches (5, 6) to compression mold a powdery material filled in the die bore when the upper punch and the lower punch being paired pass between upper rolls (12, 14) and lower rolls (13, 15), the rotary compression molding machine further comprising: an upper punch retaining portion disposed above the table and including a retaining bore receiving and retaining the upper punch, and configured to horizontally rotate along with the table and the upper punch; a dust-proofing device comprising a sealing case including a bottom wall that has an insertion bore penetrated by the upper punch and faces a downward surface of the upper punch retaining portion, and an outer wall rising from an outer edge of the bottom wall and facing an outer surface of the upper punch retaining portion, and supported by the upper punch retaining portion, and an expandable dust cover attached to be in contact with a downward surface of the bottom wall of the sealing case and covering a circumferential edge of the insertion bore and an outer circumference of the upper punch projecting downward from the bottom wall through the insertion bore; and air passages (714, 715, 717) disposed between the outer wall of the sealing case and the outer surface of the upper punch retaining portion as well as between the bottom wall of the sealing case and the downward surface of the upper punch retaining portion and communicating with an internal space of the dust cover expanding or contracting in accordance with vertical motion of the upper punch, characterized in that the air passages (714, 715, 717) are disposed for air circulation between the internal space of the expanding and contracting dust cover and the outside. an upper punch retaining portion disposed above the table and including a retaining bore receiving and retaining the upper punch, and configured to horizontally rotate along with the table and the upper punch; a dust-proofing device comprising a sealing case including a bottom wall that has an insertion bore penetrated by the upper punch and faces a downward surface of the upper punch retaining portion, and an outer wall rising from an outer edge of the bottom wall and facing an outer surface of the upper punch retaining portion, and supported by the upper punch retaining portion, and an expandable dust cover attached to be in contact with a downward surface of the bottom wall of the sealing case and covering a circumferential edge of the insertion bore and an outer circumference of the upper punch projecting downward from the bottom wall through the insertion bore; and air passages (714, 715, 717) disposed between the outer wall of the sealing case and the outer surface of the upper punch retaining portion as well as between the bottom wall of the sealing case and the downward surface of the upper punch retaining portion and communicating with an internal space of the dust cover expanding or contracting in accordance with vertical motion of the upper punch, characterized in that the air passages (714, 715, 717) are disposed for air circulation between the internal space of the expanding and contracting dust cover and the outside.