PURPOSE: To provide connection method of a coupling member and a motor and enable floating of a head of a coupling A member from a plate by a specified rate even when a motors which have different length from a motor shaft base to a cylindrical shaft abutting surface are used.

CONSTITUTION: Length of a cylindrical shaft 3 in a coupling member 1 is so set that a head 2 of the coupling member 2 is floated by a specified rate from a plate 9 when the motor which is longest from a motor shaft 6 to a cylindrical shaft abutting surface 7 is used. ' When a motor 5B which is short to the cylindrical shaft abutting surface 7 is used, the floating rate is secured by arranging a spacer 13 of a low frictional coefficient between the head 2 of the coupling member and the plate 9.