To obtain a disk free from unequal curing by radiating a cation type UV curing compsn. with UV rays prior to coating application on disk substrates and then spreading the compsn. with the disk substrates.

After the disk substrate 4 is placed on a table 3, the cation type UV curing compsn. is applied to an annular form on the surface of the disk substrate 4 while the table 3 is kept rotated. The cation type UV curing compsn. 5 is irradiated with the UV rays by a UV irradiation means 2 after the compsn. is dropped from the front end of a nozzle 1 and before the compsn. is applied on the disk substrate 4. Two sheets of the disk substrates coated with the cation type UV curing compsn. 5 in such a manner are prepd. and are bonded together after the surfaces dropped with the cation type UV curing compsn. to the annular form are disposed to face each other. Namely, the cation type UV curing compsns. are brought into contact with each other in the state of inclining the other disk substrate with the one disk substrate and are lowered until the disk substrates are paralleled with each other.