PURPOSE: To provide a method of filling a fluid in a vibration absorber in such a way that the stroke of a diaphragm is prevented from being limited at the time of vibrational load input due to the expansion of the diaphragm onto the lid side at the fitting time and that load is hardly applied to the diaphragm in the static load applied state.

CONSTITUTION: There is provided a process of forming holes 10, 11, communicated with outside, at an air chamber R surrounded by the rubber elastic body 2 of a body part 1 so as to suck air in the air chamber R from these holes 10, 11 and thereby to suck a diaphragm 4 toward the partition plate 3 side. After the stop of suction from the holes 10, 11, a specified quantity of a fluid L is filled in the vacuum chamber R, and the holes 10, 11 are sealed after the filling of the fluid L.