A mode-locked solid-state laser apparatus comprising: a resonator having a linear form; a solid-state laser medium arranged in said resonator; a saturable absorber which is arranged at one end of said resonator for inducing mode locking and is a semiconductor saturable absorbing mirror, an excitation optical system configured to inject excitation light (L 0) into said solid-state laser medium and including an excitation-light injection optical unit, configured to inject said excitation light (L 0) along a direction intersecting an optical axis of the resonator, and a dichroic mirror, arranged on the optical axis, configured to reflect toward said solid-state laser medium the excitation light (L 0) injected into the resonator and to allow transmission of pulsed light, oscillating in said resonator being linearly polarized in a first direction, a cavity dumping mechanism, configured to extract from said resonator the pulsed light oscillating in the resonator and including an electro-optical modulator, configured to change a direction of polarization of the pulsed light, a negative group-velocity dispersion compensator which is arranged at another end of said resonator and is a negative-dispersion mirror, wherein said resonator is realized by the semiconductor saturable absorbing mirror and the negative-dispersion mirror, wherein said electro-optical modulator is configured to rotate, upon application of a voltage, a linear polarization of the pulsed light in the first direction by 90 degrees so that the pulsed light changes the linear polarization to a second direction which is perpendicular to the first direction, and wherein said dichroic mirror also has the function of a deflector configured to deflect, by reflection, light linearly polarized in said second direction to a direction intersecting an optical axis of the resonator after the pulsed light undergoes said change of direction of polarization by the electro-optical modulator. a resonator having a linear form; a solid-state laser medium arranged in said resonator; a saturable absorber which is arranged at one end of said resonator for inducing mode locking and is a semiconductor saturable absorbing mirror, an excitation optical system configured to inject excitation light (L 0) into said solid-state laser medium and including an excitation-light injection optical unit, configured to inject said excitation light (L 0) along a direction intersecting an optical axis of the resonator, and a dichroic mirror, arranged on the optical axis, configured to reflect toward said solid-state laser medium the excitation light (L 0) injected into the resonator and to allow transmission of pulsed light, oscillating in said resonator being linearly polarized in a first direction, a cavity dumping mechanism, configured to extract from said resonator the pulsed light oscillating in the resonator and including an electro-optical modulator, configured to change a direction of polarization of the pulsed light, a negative group-velocity dispersion compensator which is arranged at another end of said resonator and is a negative-dispersion mirror, wherein said resonator is realized by the semiconductor saturable absorbing mirror and the negative-dispersion mirror, wherein said electro-optical modulator is configured to rotate, upon application of a voltage, a linear polarization of the pulsed light in the first direction by 90 degrees so that the pulsed light changes the linear polarization to a second direction which is perpendicular to the first direction, and wherein said dichroic mirror also has the function of a deflector configured to deflect, by reflection, light linearly polarized in said second direction to a direction intersecting an optical axis of the resonator after the pulsed light undergoes said change of direction of polarization by the electro-optical modulator.