A rotary die cutter including: a knife cylinder; an anvil cylinder that faces the knife cylinder; a blade swivel having an arc shape section installed to the outer circumference face of the knife cylinder; a punching blade attached to the blade swivel and configured to punch a hole through a sheet fed between the knife cylinder and the anvil cylinder with the punching blade, and a device for installing the blade swivel, characterized in that said device comprises: a plurality of first penetrating holes formed on the outer circumference of the knife cylinder; a plurality of first extruding members (74, 110, 112, 114, 120, 122, 128) movably placed one inside each of the first penetrating holes; a second penetrating hole formed on the blade swivel so as to have a long side along the axis direction of the knife cylinder and facing the plurality of first penetrating holes; a second extruding member (82, 102, 104, 106, 108, 121) movably placed inside the second penetrating hole and able to be brought into contact with the first extruding members (74, 110, 112, 114, 120, 122, 128); an eccentric cylinder that is disposed inside the knife cylinder for extruding the first extruding members (74, 110, 112, 114, 120, 122, 128) to outside when the punched chip (a) is to be extruded; a movable fixer for moving the blade swivel on the knife cylinder along the longitudinal axis direction of the knife cylinder, and for fixing the blade swivel to the knife cylinder; and a recess groove that is formed on the inner opening of the second penetrating hole of the blade swivel along the axis direction of the knife cylinder so that the first extruding members (74, 110, 112, 114, 120, 122, 128) can project from an outer circumference face of the knife cylinder without contacting said groove. a knife cylinder; an anvil cylinder that faces the knife cylinder; a blade swivel having an arc shape section installed to the outer circumference face of the knife cylinder; a punching blade attached to the blade swivel and configured to punch a hole through a sheet fed between the knife cylinder and the anvil cylinder with the punching blade, and a device for installing the blade swivel, characterized in that said device comprises: a plurality of first penetrating holes formed on the outer circumference of the knife cylinder; a plurality of first extruding members (74, 110, 112, 114, 120, 122, 128) movably placed one inside each of the first penetrating holes; a second penetrating hole formed on the blade swivel so as to have a long side along the axis direction of the knife cylinder and facing the plurality of first penetrating holes; a second extruding member (82, 102, 104, 106, 108, 121) movably placed inside the second penetrating hole and able to be brought into contact with the first extruding members (74, 110, 112, 114, 120, 122, 128); an eccentric cylinder that is disposed inside the knife cylinder for extruding the first extruding members (74, 110, 112, 114, 120, 122, 128) to outside when the punched chip (a) is to be extruded; a movable fixer for moving the blade swivel on the knife cylinder along the longitudinal axis direction of the knife cylinder, and for fixing the blade swivel to the knife cylinder; and a recess groove that is formed on the inner opening of the second penetrating hole of the blade swivel along the axis direction of the knife cylinder so that the first extruding members (74, 110, 112, 114, 120, 122, 128) can project from an outer circumference face of the knife cylinder without contacting said groove. a plurality of first penetrating holes formed on the outer circumference of the knife cylinder; a plurality of first extruding members (74, 110, 112, 114, 120, 122, 128) movably placed one inside each of the first penetrating holes; a second penetrating hole formed on the blade swivel so as to have a long side along the axis direction of the knife cylinder and facing the plurality of first penetrating holes; a second extruding member (82, 102, 104, 106, 108, 121) movably placed inside the second penetrating hole and able to be brought into contact with the first extruding members (74, 110, 112, 114, 120, 122, 128); an eccentric cylinder that is disposed inside the knife cylinder for extruding the first extruding members (74, 110, 112, 114, 120, 122, 128) to outside when the punched chip (a) is to be extruded; a movable fixer for moving the blade swivel on the knife cylinder along the longitudinal axis direction of the knife cylinder, and for fixing the blade swivel to the knife cylinder; and a recess groove that is formed on the inner opening of the second penetrating hole of the blade swivel along the axis direction of the knife cylinder so that the first extruding members (74, 110, 112, 114, 120, 122, 128) can project from an outer circumference face of the knife cylinder without contacting said groove.