A liquid sealed cylinder vibration preventing apparatus including a main shaft metal fitting, an intermediate cylinder metal fitting outside the main shaft substantially coaxial and having windows facing each other in a diameter direction, a rubber elastic body between the main shaft and intermediate cylinder metal fittings to connect the main shaft and intermediate cylinder metal fittings and having a recess opened to each window, a first diaphragm on one of the windows and disposed in one of the recesses, an orifice forming member on the rubber elastic body, the orifice forming member forming a main liquid chamber, a sub liquid chamber, a first orifice passage and a second orifice passage, an outer cylindrical metal fitting outside the intermediate cylinder metal fitting substantially coaxial and having a communicate window communicated with atmosphere, and a second diaphragm held by the outer cylinder metal fitting and facing the second orifice passage.