| abstract |
A coated optical fiber 1 comprising a glass fiber 10 and a primary coating layer 20 on the outer circumference of the glass fiber 10 , wherein a resin constituting the primary coating layer 20 contains ingredient(s) having a molecular weight of more than 1,000, which is extracted with methyl ethyl ketone, in an amount of 5% by weight or more and 21% by weight or less and has a Young's modulus of 0.2 to 1.0 MPa. The resin constituting the primary coating layer 20 of the coated optical fiber 1 has a good curability, and the coated optical fiber 1 exhibits a reduced microbending loss. |