Conductivity of a photoconductive layer 420 changes in accordance with a display pattern made of black and white, which is displayed on a display device 200 of a touch panel apparatus with tactile display function 10. With this change of the conductivity, viscosity of an electrorheological fluid layer 430 changes in accordance with this display pattern. This change of the viscosity is presented to an operator, as tactile information corresponding to the display pattern displayed as the visual information.