A fluid filled vibration damping device including: a main rubber elastic body connecting first and second mounting members; a partition member and a fastening member axially superposed together and secured fitting into the second mounting member. The partition member has a recess on a side of the fastening member, where an annular mounting fitting having a flange portion is inserted with a seal rubber projection disposed on one axial end thereof and projecting axially outward from the flange portion pressed fluid-tightly in an axial direction against the partition member around an entire circumference. An other axial end of the mounting fitting is fastened fluid-tightly onto a mating projection portion formed on the fastening member via a seal rubber layer. A diametrical gap is formed between an inside face of the recess of the partition member and the flange portion of the mounting fitting as well as the seal rubber projection.