A fiber laser device comprising: a seed laser light source configured to output seed laser light; a pumping light source configured to output pumping light; an amplification optical fiber configured to receive the seed laser light and the pumping light, amplify the seed laser light, and output the seed laser light as laser light; an output unit configured to output the laser light output from the amplification optical fiber; a control unit configured to control at least the seed laser light source and the pumping light source; and an output instructing unit configured to input an output instruction to the control unit, the output instruction causing the output unit to output the laser light, wherein: the control unit is configured to control the seed laser light source and the pumping light source to enter a pre-pumped state for a predetermined period of time (Ta) when the output instruction is input to the control unit; in the pre-pumped state, the seed laser light source is configured not to output the seed laser light while the pumping light source outputs the pumping light for the predetermined period of time (Ta); the control unit is configured to control, after the predetermined period of time (Ta), the seed laser light source and the pumping light source to enter an output state; and in the output state, the seed laser light source is configured to output the seed laser light, and the pumping light source is configured to output the pumping light, to cause the output unit to output the laser light, characterised in that the amplification optical fiber is doped with a rare-earth element, the rare-earth element being pumped by the pumping light; and the control unit is configured to determine an intensity (R1, R2) of the pumping light in the pre-pumped state based on a duration of a period of time from when the output state prior to the input of the output instruction to the control unit comes to an end till when the output instruction is input to the control unit. a seed laser light source configured to output seed laser light; a pumping light source configured to output pumping light; an amplification optical fiber configured to receive the seed laser light and the pumping light, amplify the seed laser light, and output the seed laser light as laser light; an output unit configured to output the laser light output from the amplification optical fiber; a control unit configured to control at least the seed laser light source and the pumping light source; and an output instructing unit configured to input an output instruction to the control unit, the output instruction causing the output unit to output the laser light, the control unit is configured to control the seed laser light source and the pumping light source to enter a pre-pumped state for a predetermined period of time (Ta) when the output instruction is input to the control unit; in the pre-pumped state, the seed laser light source is configured not to output the seed laser light while the pumping light source outputs the pumping light for the predetermined period of time (Ta); the control unit is configured to control, after the predetermined period of time (Ta), the seed laser light source and the pumping light source to enter an output state; and in the output state, the seed laser light source is configured to output the seed laser light, and the pumping light source is configured to output the pumping light, to cause the output unit to output the laser light, characterised in that the amplification optical fiber is doped with a rare-earth element, the rare-earth element being pumped by the pumping light; and the control unit is configured to determine an intensity (R1, R2) of the pumping light in the pre-pumped state based on a duration of a period of time from when the output state prior to the input of the output instruction to the control unit comes to an end till when the output instruction is input to the control unit.