PURPOSE: To decrease the correcting works for an upper and a lower surface reference boards with a correcting carrier, which is used in a plane polishing machine for simultaneous polishing of both planes of a work, and prevent the carrier from cracking by providing it with accommodation holes of rectangular form, and locating these holes under the specified conditions determined relative to the peripheries of the upper and lower boards.

CONSTITUTION: Rectangular accommodation holes 4 are arranged on a circumference divided equally into five segments, and the perpendicular bisector (a) to that edge of each rectangular hole 4 which is nearer the periphery shall be dislocated by an amount (e, f, g) in parallel shift from the straight line (b) passing the center of a carrier 5. Associate therewith the distance (h, i, j) of that edge of the hole 4, which is nearer the carrier center, from the carrier center shall be closer to the carrier center as the dislocation amount (e, f, g) is greater. In the position where that edge of the hole 4 which is near the carrier periphery is parallel with the tangent to an upper and a lower surface reference board 6, 7, the distance L of this edge from the tangent shall be as small as practicable.