To constitute a twin screw pump handling a two-phase fluid of liquid and gas in such a way as to be able to pump only gas even in the vertical attitude of the pump and to be able to feed fluids with equal gas content to two feed-in ports.

A twin screw pump has two pairs of conical screws 4 (8, 9) and 5 (14, 15) arranged vertically, and two feed-in ports 16, 17 thereof are fed with two-phase fluids independently of each other by a flow divider 33. Two screw shafts 10-12, 11-14 respectively have center axial holes 40, 41 that connect a delivery chamber 21 to a series of radial passages 42 each of which ends at the tip part of a single tooth of a thread. The flow divider 33 is formed of a horizontal expansion/separation barrel 34, and this barrel has a vertical division wall 36 that divides the interior of the barrel in two parts so as to form two equal chambers 32.