A fixed abrasive-grain processing device used in production of a plurality of semiconductor wafers, the device comprising: a disk-shaped lower surface-plate horizontally disposed; a lower fixed abrasive-grain layer that is adjacent to the top surface of the lower surface-plate and that grinds the top surfaces of the plurality of semiconductor wafers; a first motor that rotates the lower surface-plate around an axis (O 1) of rotation; a disk-shaped upper surface-plate that horizontally overlies the lower surface-plate; an upper fixed abrasive-grain layer that is adjacent to the bottom surface of the upper surface-plate and that grinds the bottom surfaces of the plurality of semiconductor wafers; a second motor that rotates the upper surface-plate around the axis (O 1) of rotation; a carrier plate that is horizontally interposed between the lower surface-plate and the upper surface-plate and that includes a plurality of holes each accommodating one of the plurality of semiconductor wafers; a carrier rotating device that circularly moves the carrier plate; a press mechanism that presses one of or both the lower surface-plate and the upper surface-plate in such a direction that the lower and the upper surface-plates (2,3) come close to each other; a first intermediate layer that is interposed between the lower fixed abrasive-grain layer and the top surface of the lower surface-plate; and a second intermediate layer that is interposed between the upper fixed abrasive-grain layer and the bottom surface of the upper surface-plate, wherein: the lower fixed abrasive-grain layer and the upper fixed abrasive-grain layer include abrasive grain having a diameter of 4 μm or less and being dispersed and fixed in elastic members; characterised in that the press mechanism is configured such that the lower surface-plate and the upper surface-plate apply pressure of 250-400 g/cm2 to the top surfaces and the bottom surfaces of the plurality of semiconductor wafers, respectively, and the lower fixed abrasive-grain layer and the upper fixed abrasive-grain layer each have a thickness of 100-2000 μm. a disk-shaped lower surface-plate horizontally disposed; a lower fixed abrasive-grain layer that is adjacent to the top surface of the lower surface-plate and that grinds the top surfaces of the plurality of semiconductor wafers; a first motor that rotates the lower surface-plate around an axis (O 1) of rotation; a disk-shaped upper surface-plate that horizontally overlies the lower surface-plate; an upper fixed abrasive-grain layer that is adjacent to the bottom surface of the upper surface-plate and that grinds the bottom surfaces of the plurality of semiconductor wafers; a second motor that rotates the upper surface-plate around the axis (O 1) of rotation; a carrier plate that is horizontally interposed between the lower surface-plate and the upper surface-plate and that includes a plurality of holes each accommodating one of the plurality of semiconductor wafers; a carrier rotating device that circularly moves the carrier plate; a press mechanism that presses one of or both the lower surface-plate and the upper surface-plate in such a direction that the lower and the upper surface-plates (2,3) come close to each other; a first intermediate layer that is interposed between the lower fixed abrasive-grain layer and the top surface of the lower surface-plate; and a second intermediate layer that is interposed between the upper fixed abrasive-grain layer and the bottom surface of the upper surface-plate, wherein: the lower fixed abrasive-grain layer and the upper fixed abrasive-grain layer include abrasive grain having a diameter of 4 μm or less and being dispersed and fixed in elastic members; characterised in that the press mechanism is configured such that the lower surface-plate and the upper surface-plate apply pressure of 250-400 g/cm2 to the top surfaces and the bottom surfaces of the plurality of semiconductor wafers, respectively, and the lower fixed abrasive-grain layer and the upper fixed abrasive-grain layer each have a thickness of 100-2000 μm. the lower fixed abrasive-grain layer and the upper fixed abrasive-grain layer include abrasive grain having a diameter of 4 μm or less and being dispersed and fixed in elastic members; characterised in that the press mechanism is configured such that the lower surface-plate and the upper surface-plate apply pressure of 250-400 g/cm2 to the top surfaces and the bottom surfaces of the plurality of semiconductor wafers, respectively, and the lower fixed abrasive-grain layer and the upper fixed abrasive-grain layer each have a thickness of 100-2000 μm.