PURPOSE: To improve strength of adhesion by simultaneously irradiating a photosetting type joining material with a UV laser and a laser of a specific wavelength, thereby joining a plastic substrate and a glass substrate.

CONSTITUTION: Seals consisting of a UV curing type resin are formed in prescribed patterns on the glass substrate 5 and spacers are sprayed on the plastic substrate 4 on one side. The plastic substrate 4 and the glass substrate 5 are stuck to each other and while both substrates are pressed by using a press machine having a quartz platen 10 as a pressing bed, the seals are simultaneously irradiated with the xenon fluorine excimer laser 12 and the CO2 laser 14 (wavelength 10.6μm). At this time, the substrates may be irradiated with a laser of an oscillation wavelength 600nm to 0.1mm, for example, helium neon laser or Nd3+-doped YAG laser in place of the CO2 laser 14. Liquid crystals are thereafter billed between the substrates 4 and 5.