A cylindrical hydraulic engine mount with simple construction has been developed which has a sub chamber formed without diaphragm by utilizing air compressibility. An analysis model of the mount is presented to predict the non-linear dynamic characteristics in consideration of the effect of excitation amplitude on the dynamic stiffness and loss factor. The calculated dynamic characteristics are in good agreement with experimental results. By using the analysis model, the effect of the volume and pressure of air on the dynamic characteristics is clarified. On-vehicle test on a chassis dynamometer shows that the newly developed hydraulic engine mount has same effect on ride comfort improvement as a conventional hydraulic mount.