To provide a method and device for screening an optical fiber core, and a method for manufacturing an optical fiber core that can suppress occurrence of damage in resin coating layers of optical fiber, a screening method applies a guaranteed tensile strain set as a guaranteed value to the optical fiber core with a resin coating layer. The method includes a pre-strain applying step of adding a tensile force while feeding a portion of the optical fiber core retained at both ends of the portion and applying a pre-tensile strain smaller than the guaranteed tensile strain, a guaranteed strain applying step of adding a tensile force while feeding the portion of the optical fiber core retained at both ends of the portion and applied with the pre-tensile strain, and applying the guaranteed tensile strain just for a predetermined time, and a strain releasing step of releasing the optical fiber core from the guaranteed tensile strain.