In this paper, a translational actuation mechanism in the form of a parallel-crank mechanism (i.e. double-crank 4-bar mechanism) articulated with two dielectric elastomer actuators working in parallel are fabricated. This structure, which is a fully soft mechanism, is established by stretching a dielectric elastomer (DE) film over a PET (polyethylene terephthalate) frame so that the energy released from the stretched DE film is stored in the frame as bending energy. The mechanism generates a translational output under a driving voltage applied between two electrodes of the DE film. The visco-elastic models are proposed for the mechanism so that the mechanical properties of the actuator can more accurately be incorporated into the mechanism model. The proposed model accurately predicts the experimental frequency response of the mechanism at different voltages.