Provided is a silphenylene-containing photocurable composition including: (A) a specific silphenylene having both terminals modified with alicyclic epoxy groups, and (C) a photoacid generator that generates acid upon irradiation with light having a wavelength of 240 to 500 nm. Also provided is a pattern formation method including: (i) forming a film of the photocurable composition on a substrate, (ii) exposing the film through a photomask with light having a wavelength of 240 to 500 nm, and if necessary, performing heating following the exposure, and (iii) developing the film in a developing liquid, and if necessary, performing post-curing at a temperature within a range from 120 to 300° C. following the developing. Further provided is an optical semiconductor element obtained by performing pattern formation using the method. The composition is capable of very fine pattern formation across a broad range of wavelengths, and following pattern formation, yields a film that exhibits a high degree of transparency and superior light resistance. The composition may also include: (B) a specific epoxy group-containing organosilicon compound.