The present invention relates to an apparatus for measuring a residual stress of an optical fiber. More particularly, the present invention relates to an apparatus for measuring residual stress of an optical fiber which is provided with a variable polarizer of which rotation is unnecessary instead of a rotary analyzer to measure the residual stress in high resolution and at high speed.There is provided an apparatus for measuring a residual stress of an optical fiber including a light generation unit that generates light; a lens unit that converts the generated light into collimated light; a polarization unit including variable polarization devices that divide the collimated light into two perpendicularly polarized light beams and control phase retardation of the polarized light beams by means of an electrical signal; a measurement unit that allows the divided light beams of two polarization states to penetrate an optical fiber to be measured; and a light detection unit that detects the polarization states of the light beams penetrating the optical fiber.