An optical fiber including a glass core, and a polymer cladding formed around the glass core, the polymer cladding containing a mixture of a polymerizable composition and a silane coupling agent, and a fluorine-based ultraviolet curable resin. The mixture contains 5 to 95 parts by weight of the silane coupling agent based on 100 parts by weight of the total weight of the mixture. The fluorine-based ultraviolet curable resin alone has a refractive index in a range of 1.350 to 1.420 after ultraviolet curing. A component originated from the silane coupling agent is concentrated within a range of 20 μm or less in the polymer cladding from an interface between the glass core and the polymer cladding.