An extrusion molding system includes a die having a first opening with a unvariable shape and a second opening with a variable shape, an extruder which feeds resin to the die, and a gear pump arranged between the die and the extruder. An ECU conducts a first sequence control to change the shape of the second opening and a second sequence control to change the rotation speed of the first gear pump in synchronism with a change in the shape of the second opening.