To improve the manufacture yield by reducing display unevenness due to the cell gap of a liquid crystal display panel.

In the manufacturing process of the liquid crystal display, two substrates are put one over the other and then a process for joining them together with a seal material is improved. Namely, the two substrates are superposed one over the other across the seal material with transparent electrodes inward in a setting process for the seal material to form a repetitive unit 8 of superposition. Then repetitive units 8 of superposition are put one over another to constitute a substrate stack 7, which is set on a jig 9 dedicated to pressure application. The superposition substrate stack 7 while pressed by the dedicated jig 9 is given acoustic vibrations by an electromagnetic acoustic buzzer 10 to heat and set seal materials.