To prepare a self-adhesive sheet which firmly bonds a light-transmitting plastic film to a substrate and is kept bonded to the substrate without dimensional changes even when the light-transmitting plastic film is expanded or contracted in a heating-cooling process thereby to permit smooth progress of precise works in a working process for a liquid crystal display panel, and yet allows easy release of the light-transmitting plastic film by ultraviolet irradiation after processes for the liquid crystal display panel are finished.

The self-adhesive sheet has a three-layered structure comprising a UV self-adhesive layer, a substrate and a self-adhesive layer laminated in this order. The self-adhesive sheet firmly bonds before ultraviolet irradiation to the light- transmitting plastic film laid on the UV self-adhesive layer and to the substrate for fixing arranged under the self-adhesive layer, and yet, after ultraviolet irradiation, undergoes deterioration in the adhesive force only to the light-transmitting plastic film to be easily peeled from the light-transmitting plastic film. When the light- transmitting plastic film is laid on the UV self-adhesive layer and heated, the ratio of the size change in the light-transmitting plastic film after heating measured at room temperature to the size of the light-transmitting plastic film before heating measured at room temperature is at most 0.1%.