Crosslinking reaction of polymer by ultraviolet (UV) irradiation has been important in industries. In this work, photocrosslinking of styrene-isoprene-styrene (SIS) triblock copolymer in the presence of benzoin photoinitiator and a dimethacrylate monomer as crosslinking agent was investigated. Curing of samples was initiated under UV irradiation. Benzoin was used as photoinitiator because it contains chromophore group that could absorb UV irradiation. Ethylene glycol dimethacrylate (EGDMA) was used as crosslinking agent, since it has alkene functional groups that could react with the alkene group of SIS. ATR-FTIR spectra of samples show that absorption band of double bond at 1500-1600 cm(-1) decreases after UV exposure. Increasing the concentration of benzoin (0.1-1 phr) and EGDMA (1-10 phr) leads to an increase in gel content and hardness, while swelling ratio decreases. After 5 min heating at 150 degrees C, about 20%wt of the unirradiated compound became insoluble, because heating of compound at 150 degrees C causes crosslinking reaction without any irradiation.