A post-formation filling type fluid filled vibration damping device wherein a first communication groove, which interconnects a plurality of through holes, is formed in a partition member that separates a pressure receiving chamber and an equilibrium chamber, the groove being formed in a surface of the partition member that opposes a flexible membrane. In addition, a second communication groove, which connects an orifice passage and at least one of the plurality of through holes, is formed in the surface of the partition member that opposes the flexible membrane.