PURPOSE: To obtain a motor which can be coupled to a frame without deforming a mounting plate, whose feed accuracy is high and whose performance is high by a method wherein the diameter of a fixing screw at a face coming into contact with the mounting plate is set at a specific size.

CONSTITUTION: The side of the coupling face to a motor 2 of a mounting plate 14 is provided with a guide-shaft force-fitting hole 14a and with a fixing-screw insertion hole 14b whose diameter is larger than the nominal diameter of at least a fixing screw 17. A face opposite to the coupling face is provided with a guide-shaft fitting and insertion hole 14c whose diameter is larger than that of a guide shaft 6. The guide-shaft force-fitting hole 14a is formed in such a way that a guide-shaft insertion port is narrow and that a port opposite to the insertion port is wide. In addition, the diameter in a face coming into contact with the mounting plate of the fixing screw 17 is set at 1.7 to 1.8 times that of the fixing-screw insertion hole 14b, at 1.9 to 2 times the nominal diameter of the fixing screw and at 2.7 to 2.8 times the plate thickness of the mounting plate. Thereby, it is possible to obtain the motor which can be coupled to a frame without deforming the mounting plate, whose feed accuracy is high and whose performance is high.