PURPOSE: To provide a fluid-filled vibration isolator assembling method enabling the state of tension being hardly applied to a diaphragm used for the vibration isolator during its use and also enabling the effective use of an air chamber on the diaphragm expanded side.

CONSTITUTION: There are provided a process of filling a specified quantity of a fluid L into a fluid chamber A formed at a body part 1 formed of a rubber elastic body 2 as a main body and setting the body part 1, in a vacuum drum 10, a process of setting a partition plate 9 and a diaphragm 6 as well as a lid 4 to the body part 1 and obtaining the state of enabling the suction of air on the fluid surface before sealing these members 4, 6, 9 for rigid fixing, and a process of letting air out of the vacuum drum 10 to place the inside of the drum 10 in the vacuum state. There are further provided a process of sealing the body part 2, the partition plate 9, the diaphragm 6 and the lid 4 in the vacuum state of the drum 10 to fix them mutually, and a process of taking the body part 2 out of the vacuum drum 10 and letting air enter into the lid 4 from an opening 15 formed at the lid 4.