PURPOSE: To highly accurately grind the minute hole by applying pressure to one end of the hole being machined to supply grinding fluid and sucking from the other end to apply a negative pressure so that the grinding fluid uniformly acts over the whole surface of the hole being machined.

CONSTITUTION: To grind the hole 2; the grinding fluid is spouted from a nozzle 5 and allowed to flow from a guide hole 3 into the hole 2 being machined, as a suction means 10 is operated to suck the grinding fluid from a suction hole 7 of a jig 8. Consequently, the suction means 10 applies a high negative pressure to the suction hole 7 side, so that a negative pressure in the direction of an arrow B is applied to the grinding fluid 6 from an outlet 21 side, and the grinding fluid 6 is sucked by the negative pressure. Therefore, a uniform grinding pressure by the grinding fluid flow is applied on the whole surface of the hole 2 being machined, from an inlet 22 side to the outlet 21 side of the grinding fluid, so that the whole surface of the hole 2 can be uniformly ground.