PURPOSE: To provide the non-loss dispersion compensation fiber which compensates dispersion and lessens the loss of the non-loss dispersion compensation fiber itself to zero and the non-loss dispersion compensation device constituted by using this fiber.

CONSTITUTION: This non-loss dispersion compensation optical fiber compensates the dispersion by doping a rare earth element into the core part of an optical fiber having large negative dispersion and transmitting signal light in the state of exciting the fiber 4 by using an exciting light source 2. The non-loss dispersion compensation device constituted by using the above-mentioned optical fiber 4 has the optical fiber 4 which has a negative large dispersion value and has the length to compensate the desired accumulated dispersion value of a transmission line and is added with the rare earth element for the purpose of light amplification in a desired wavelength band, the exciting light source 2 which generates exciting light and an optical coupler 3 which makes the exciting light and the signal light incident on the inside of the optical fiber.