A colored optical fiber whose transmission loss hardly increases even in a high humidity condition or water-immersed condition is provided. The colored optical fiber according to the present invention is a colored optical fiber having a colored coating layer on a circumference of an optical fiber having at least two coating layers on a circumference of a glass optical fiber, characterized in that a difference in each amount of thermal expansion in an outer diameter direction between the optical fiber and a coating layer obtained by removing the glass optical fiber from the optical fiber in a temperature range from -100.degree. C. to 100.degree. C. is 1.8 .mu.m or less.