Abstract Electrorheological fluids (ERF) are functional fluids whose viscoelastic property varies according to the intensity of the applied electric field. The disadvantages of ERF are the sedimentation of ER particles and the requirement of a seal mechanism. In order to solve these problems, gel structured electrorheological fluids (ERG) are developed in this study. The basic characteristics of the ERG film are experimentally analyzed. The ERG is applied to the clamping mechanism of aerostatic slider. By using the ERG element, the aerostatic slider can be clamped with extremely low clamping force. The ERG clamp also serves as a variable damping element of aerostatic slider.