Abstract: A variable-focus optical device comprises an elastomeric member having a gradient of shear modulus along its optical axis, and a deforming member having an aperture adapted for causing projection or sinking of the elastomeric member therethrough or thereat to deform the surface of the elastomeric member. The gradient of shear modulus is preferably one of continuously decreasing from the surface toward the inside of the elastomeric member. The gradient of shear modulus is provided by a concentration gradient of an inorganic substance such as silica dispersed in an elastomeric substance such as polysilioxane.