A semiconductor laser element comprising: (a) a stacked structure body in which a first compound semiconductor layer having a first conductivity type and made of a compound semiconductor, a third compound semiconductor layer configured to form a light emitting region and a saturable absorption region made of a compound semiconductor, and a second compound semiconductor layer having a second conductivity type different from the first conductivity type and made of a compound semiconductor are sequentially stacked; (b) a second electrode; and (c) a first electrode electrically connected to the first compound semiconductor layer, wherein a ridge stripe structure formed of at least part of the stacked structure body is formed, a side structure body (72A, 72B) formed of the stacked structure body is formed on both sides of the ridge stripe structure, the second electrode formed on the second compound semiconductor layer forming the ridge stripe structure is separated into a first portion configured for sending a direct current to the first electrode via the light emitting region to create a forward bias state and a second portion configured for applying a reverse electric field to the saturable absorption region, a protection electrode is formed on the second compound semiconductor layer on a portion up to near or up to or over a shoulder (72") of at least one of the side structure bodies (72A, 72B) which portion is facing the second portion of the second electrode, an insulating film made of an oxide insulating material is formed to extend on said portion of the ridge stripe structure and up to said portion of the side structure body (72A, 72B), so that the insulating film is formed where neither the second electrode nor the protection electrode is formed, and the second portion of the second electrode and the protection electrode are covered by a second lead-out wiring layer formed on the insulating film, so that when a voltage is applied to the second portion of the second electrode, the same voltage is applied to the protection electrode. (a) a stacked structure body in which a first compound semiconductor layer having a first conductivity type and made of a compound semiconductor, a third compound semiconductor layer configured to form a light emitting region and a saturable absorption region made of a compound semiconductor, and a second compound semiconductor layer having a second conductivity type different from the first conductivity type and made of a compound semiconductor are sequentially stacked; (b) a second electrode; and (c) a first electrode electrically connected to the first compound semiconductor layer, wherein a ridge stripe structure formed of at least part of the stacked structure body is formed, a side structure body (72A, 72B) formed of the stacked structure body is formed on both sides of the ridge stripe structure, the second electrode formed on the second compound semiconductor layer forming the ridge stripe structure is separated into a first portion configured for sending a direct current to the first electrode via the light emitting region to create a forward bias state and a second portion configured for applying a reverse electric field to the saturable absorption region, a protection electrode is formed on the second compound semiconductor layer on a portion up to near or up to or over a shoulder (72") of at least one of the side structure bodies (72A, 72B) which portion is facing the second portion of the second electrode, an insulating film made of an oxide insulating material is formed to extend on said portion of the ridge stripe structure and up to said portion of the side structure body (72A, 72B), so that the insulating film is formed where neither the second electrode nor the protection electrode is formed, and the second portion of the second electrode and the protection electrode are covered by a second lead-out wiring layer formed on the insulating film, so that when a voltage is applied to the second portion of the second electrode, the same voltage is applied to the protection electrode.