A composition for a gasket which comprises (A) 100 parts by weight of a urethane acrylate oligomer having a weight-average molecular weight of 7,000 to 40,000, (B) 40 to 260 parts by weight of a polyether monoacrylate substituted at the end and/or a polyether polyester monoacrylate substituted at the end, and (C) 0.5 to 5 parts by weight of a photopolymerization initiator and has a viscosity of 4,000 to 100,000 centipoises at 25.degree. C.; and a process for producing a gasket by discharging the above composition on a substrate by using an X-Y-Z-driving automatic coating robot and curing the discharged composition by irradiation of ultraviolet light.A gasket can be formed to an accurate shape. Operations of forming and attaching the gasket can easily be conducted, and loss of the used material can be reduced. The gasket has a large tearing strength and a small compression set and is excellent in the flexibility and the sealing property. Contamination of the inside of containers of high precision instruments with volatile matters generated from the gasket can be prevented.