An extruder comprises an extruding section, a chamber drum, and a forming section. The extruding section kneads and extrudes a kneaded material including a ceramic raw material. The chamber drum includes a first space portion which extends from the extrusion port side of the extruding section in an extruding direction and allows the kneaded material to flow in the extruding direction, and a second space portion which extends from a downstream side of the first space portion in a downward direction, allows the kneaded material to flow in the downward direction different from the extruding direction, and has a discharge port to discharge the kneaded material. The forming section includes a die through which the kneaded material discharged through the discharge port of the chamber drum is pushed out, to extrude and form ceramic formed bodies.