To provide a working method capable of removing a caught foreign matter without separating a contactor of a sizing device (measuring means) from a work and a working device.

This working method working the work by using a rotating means, a working means 30, the measuring means, an abnormality detecting means and a fluid supplying means has; a step to rotate the work around the axis of rotation of the work by the rotating means; a step to gradually grind an outer peripheral part of the rotating work by the working means; a step to supply fluid to a contact part of the working means and the outer peripheral part by the fluid supplying means; a step to measure an outside diameter of the outer peripheral part by keeping a state making contact with the grinding outer peripheral part by the measuring means; a step to detect abnormality showing the contact part with the outer peripheral part in the measuring means catching a foreign matter by the abnormality detecting means and; a step to remove the foreign matter caught in the contact part by temporarily increasing a flow rate of the fluid supplied from the fluid supplying means in detecting the abnormality.