The present invention relates to a method for bonding together two disc substrates, at least one disc substrate having a UV transmissive-visible light reflective information recording layer provided on a UV transmission base. In this method, the disc substrates are bonded together, so that the information recording layer of one disc substrate faces the other disc substrate, by employing UV irradiation to cure a UV curable composition used as a bonding agent. In the case of the present invention, to cure the bonding agent, UV is irradiated in a single or repeating flash so as not to impair the information recording layer. As a result, the bonding agent can be cured in a shorter period of time with less energy consumed as compared to the conventional method of using conditions irradiation of UV light to cure a UV curable composition used as a bonding agent. Accordingly, the present method enables a product disc to be obtained in a shorter time, with less energy used, so that productivity (i.e., number of bondings per unit time) is improved.