PURPOSE: To enable butters mounted on a motor fan to be easily manufactured and to achieve uniform quality by simplifying the form of each buffer and to enhance operability for assembly by simplifying the installation of the buffers and to make it easy to deal with different kinds of fans and to reduce costs using common parts by enabling the buffers to be mounted in fan cases of different sizes.

CONSTITUTION: A front buffer 1 in the form of a flat ring and a circumferential buffer 2 in the form of a flat band are formed of an elastic material such as rubber or a foaming resin, with an adhesive layer provided on one side of the each buffer. The adhesive layers are used to glue the front buffer 1 to the front surface of the fan case 4 of a motor fan 3 and to glue the circumferential buffer 2 to the outer periphery of the fan case 4.