PURPOSE: To perform accurate setting of a delivery amount of a pump and a given power value by increasing a side gap between the side of a gear and a side plate proportionally along a radial direction.

CONSTITUTION: A pair of hears 6a and 6b are supported in a geared state to bearings 8a and 8b, the side plates 8a and 8b are sliced to the side 6c of each of the two gears 6a and 6b to effect slide seal of a volume space, and non-Newton fluid is fed with a pressure. Especially, side gaps SX between the side 6c of each of the gears 6a and 6b and the side plates 8a and 8b are increased proportionally along a radial direction so that a shearing speed, i.e., shearing viscosity, is kept at an approximately constant value throughout the whole are of the side. This constitution more accurately designs an internal leakage amount and a loss power compared with a conventional type and suitably dissolves a conventional trouble wherein a deviation in a delivery amount and a given power value is produced during use.