ANTI-VIBRATION DEVICE

A partition member () of an anti-vibration device () includes a membrane () and an orifice passage (), the orifice passage includes a main liquid chamber-side passage () and an auxiliary liquid chamber-side passage (), the main liquid chamber-side passage and the auxiliary liquid chamber-side passage extend in a circumferential direction and are disposed at mutually different radial positions, a flow direction in the main liquid chamber-side passage and a flow direction in the auxiliary liquid chamber-side passage are opposite to each other when liquid flows through the orifice passage, a channel cross-sectional shape in at least one passage of the main liquid chamber-side passage and the auxiliary liquid chamber-side passage is a laterally long flat shape that is short in an axial direction along a central axis () of a first attachment member and long in a radial direction, and a ratio of a radial size to an axial size in the one passage is larger than the ratio in the other passage of the main liquid chamber-side passage and the auxiliary liquid chamber-side passage.