A pulse fiber laser device comprising: an amplifying optical fiber arranged on a resonant optical path of an optical resonator; an excitation light supply unit (11, 12) configured to supply excitation light to the amplifying optical fiber; a saturable absorber arranged on the resonant optical path; a first optical fiber which has a first end face opposing the saturable absorber, guides light on the resonant optical path, and outputs the light from the first end face toward the saturable absorber; a first gradient index lens (15, 15A, 15B) which is attached to the first end face of the first optical fiber, converges the light output from the first end face of the first optical fiber, and outputs the light to the saturable absorber; and an optical output unit outputting a part of oscillation light emitted from the amplifying optical fiber with the excitation light supplied from the excitation light supply unit and oscillated in the optical resonator to the outside of the optical resonator, wherein the optical resonator is a Fabry-Perot type resonator which reciprocates the light between a first mirror and a second mirror, the saturable absorber is integrated with any of the first mirror and the second mirror to constitute a saturable absorber mirror, the first gradient index lens converges the light output from the first end face of the first optical fiber and outputs the light to the saturable absorber mirror, and inputs the light reflected from the saturable absorber mirror into the first end face of the first optical fiber, characterized in that a movable shaft is fixed at a back surface of the mirror constituting the saturable absorber mirror, the movable shaft configured to act as distance adjusting means adjusting a distance between the saturable absorber and the first gradient index lens by being moved in the axial direction and configured to act as position adjusting means adjusting an incident position of the light output from the first gradient index lens on the saturable absorber by being rotationally moved around an axis of the shaft. an amplifying optical fiber arranged on a resonant optical path of an optical resonator; an excitation light supply unit (11, 12) configured to supply excitation light to the amplifying optical fiber; a saturable absorber arranged on the resonant optical path; a first optical fiber which has a first end face opposing the saturable absorber, guides light on the resonant optical path, and outputs the light from the first end face toward the saturable absorber; a first gradient index lens (15, 15A, 15B) which is attached to the first end face of the first optical fiber, converges the light output from the first end face of the first optical fiber, and outputs the light to the saturable absorber; and an optical output unit outputting a part of oscillation light emitted from the amplifying optical fiber with the excitation light supplied from the excitation light supply unit and oscillated in the optical resonator to the outside of the optical resonator, wherein the optical resonator is a Fabry-Perot type resonator which reciprocates the light between a first mirror and a second mirror, the saturable absorber is integrated with any of the first mirror and the second mirror to constitute a saturable absorber mirror, the first gradient index lens converges the light output from the first end face of the first optical fiber and outputs the light to the saturable absorber mirror, and inputs the light reflected from the saturable absorber mirror into the first end face of the first optical fiber, characterized in that a movable shaft is fixed at a back surface of the mirror constituting the saturable absorber mirror, the movable shaft configured to act as distance adjusting means adjusting a distance between the saturable absorber and the first gradient index lens by being moved in the axial direction and configured to act as position adjusting means adjusting an incident position of the light output from the first gradient index lens on the saturable absorber by being rotationally moved around an axis of the shaft.