A resin liquid is provided which is used to produce an optical fiber coating layer which does not degrade over time in long-period transmission characteristics of the optical fiber. An optical fiber in which long-period transmission characteristics do not degrade is also provided. In order to achieve these objects, the present invention provides a resin liquid for an optical fiber coating layer containing at least one resin, wherein the resin liquid contains fewer than 500 pieces of extraneous material per 1 ml of the resin liquid, which have a minimum length of 0.5 .mu.m or more and a hardness greater than a hardness of the resin liquid after curing.