A method for curing an addition curable organopolysiloxane composition is provided. This method uses a UV activatable platinum catalyst (complex), and this method has enabled consistent curing of the parts where UV exposure is impossible as well as consistent curing of a thick article. This method cures an addition curable organopolysiloxane composition comprising (A) an organopolysiloxane having at least 2 alkenyl groups bonded to silicon atoms per molecule, (B) an organohydrogenpolysiloxane having at least 2 hydrogen atoms bonded to silicon atoms per molecule, and (C) an effective amount of a photoactivatable platinum complex curing catalyst, and the method comprises the first step of exposing the composition to UV to increase catalytic activity of the component (C), and the second step of applying the composition obtained in the first step to a desired position and curing the composition.