A fiber laser device comprising: a laser oscillator configured to emit laser light having a first wavelength (λ1); a first optical filter to which the laser light having the first wavelength (λ1) output from the laser oscillator is input and which is configured to transmit the laser light having the first wavelength (λ1); a wavelength converter to which the laser light having the first wavelength (λ1) that has passed through the first optical filter is input and which is configured to generate laser light having a second wavelength (λ2) that is longer than the laser light having the first wavelength (λ1) using stimulated Raman scattering caused by the laser light having the first wavelength (λ1) and transmit the laser light having the first wavelength (λ1) and the laser light having the second wavelength (λ2); a second optical filter to which the laser light having the first and second wavelengths (λ1, λ2) output from the wavelength converter are input and which is configured to transmit the laser light having the second wavelength (λ2) and to prevent transmission of the laser light having the first wavelength (λ1); an optical fiber amplifier to which the laser light having the second wavelength (λ2) that has passed through the second optical filter is input and which is configured to amplify the laser light having the second wavelength (λ2); and an output end of the fiber laser device through which the laser light having the second wavelength (λ2) amplified by the optical amplifier is output, wherein the first optical filter prevents transmission of the laser light having the second wavelength (λ2), and the first optical filter, the wavelength converter, and the second optical filter each include a photonic band gap fiber. a laser oscillator configured to emit laser light having a first wavelength (λ1); a first optical filter to which the laser light having the first wavelength (λ1) output from the laser oscillator is input and which is configured to transmit the laser light having the first wavelength (λ1); a wavelength converter to which the laser light having the first wavelength (λ1) that has passed through the first optical filter is input and which is configured to generate laser light having a second wavelength (λ2) that is longer than the laser light having the first wavelength (λ1) using stimulated Raman scattering caused by the laser light having the first wavelength (λ1) and transmit the laser light having the first wavelength (λ1) and the laser light having the second wavelength (λ2); a second optical filter to which the laser light having the first and second wavelengths (λ1, λ2) output from the wavelength converter are input and which is configured to transmit the laser light having the second wavelength (λ2) and to prevent transmission of the laser light having the first wavelength (λ1); an optical fiber amplifier to which the laser light having the second wavelength (λ2) that has passed through the second optical filter is input and which is configured to amplify the laser light having the second wavelength (λ2); and an output end of the fiber laser device through which the laser light having the second wavelength (λ2) amplified by the optical amplifier is output, wherein the first optical filter prevents transmission of the laser light having the second wavelength (λ2), and the first optical filter, the wavelength converter, and the second optical filter each include a photonic band gap fiber.