PURPOSE: To substantially eliminate precession of a steering wheel by composing it so that a first main fluid path may communicate with a return port quicker than a second fluid path.

CONSTITUTION: A first main fluid path forms a first variable cylinder control orifice A4-R between a fluid actuation means 23 and a first control fluid port 32, while a second fluid path forms a second variable cylinder control orifice A4-L between the fluid actuation means 23 and a second nature control port 34 and it is composed so that the orifice A4-R is separated more than the orifice A4-L in the axial direction from the axial end of the other valve means. In other words, the length of a leakage path in making a left turn is sufficiently shorter than in making a right turn. The timing of a variable return flow control orifice A5-R is advanced relatively to the timing of a main variable flow control orifice A1-R. Thus because fluid starts to flow fast from a main flow path to a system tank in making a right turn, the length of the leakage path being prolonged is compensated.