PURPOSE: To ensure a flow control characteristic irrespective of a flowing direction by providing a valve element having a center hole where inlet and outlet passages cross laterally, a pressure balanced cartridge assembly of normal- reverse type in which a flow control means is retained in the valve element and an operation means positioning the flow control means.

CONSTITUTION: A choke valve body 4 has a central cylindrical hole 22 receiving a cartridge assembly 6 and flow passages 24, 26 cross at right angles thereat. A directioning pin 48 for properly directioning the flow passages 24, 26 and flow passages 44, 46 in cooperation with a hole 50 at an upper surface of the body 4 is arranged radially. The assembly 6 is removed from the body 4, then turned around a horizontal axis and a vertical axis, and the pin 48 is fitted into a hole 52. When the assembly 6 is reinserted into the body 4, the pin 48 enters the hole 52, and thereby a proper direction is maintained. When a retainer cap 38 and a cap screw 62 are changed, a flow is thus allowed to move a piping portion 16 to a piping portion 14 through a choke valve 2.