A laser device comprising: a light source including a plurality of laser diodes ; and a processor comprising a driving current peak hold unit , an optical power peak hold unit and a degree-of-deterioration estimation unit ; wherein the driving current peak hold unit is configured to hold a maximum value within a predetermined period of a driving current applied to the plurality of laser diodes ; wherein the optical power peak hold unit is configured to hold a maximum value within the predetermined period of a power of light emitted from the light source when the light is emitted from each laser diode ; wherein a memory is electrically connected to the processor and stores a relationship between a magnitude of the driving current, a magnitude of the power of the light, and a degree of deterioration of the light source for different cases corresponding to different degrees of deterioration; wherein the degree-of-deterioration estimation unit is configured to determine a degree of deterioration among the different degrees of deterioration that are stored in the memory that is close to the relationship between the maximum value within the predetermined period of a power of light and the maximum value within the predetermined period of the driving current; wherein the driving current peak hold unit is configured to erase the maximum value of the driving current stored within the predetermined period after the predetermined period elapses, and the optical power peak hold unit is configured to erase the maximum value of the power of the light stored within the predetermined period after the predetermined period elapses. a light source including a plurality of laser diodes ; and a processor comprising a driving current peak hold unit , an optical power peak hold unit and a degree-of-deterioration estimation unit ; wherein the driving current peak hold unit is configured to hold a maximum value within a predetermined period of a driving current applied to the plurality of laser diodes ; wherein the optical power peak hold unit is configured to hold a maximum value within the predetermined period of a power of light emitted from the light source when the light is emitted from each laser diode ; wherein a memory is electrically connected to the processor and stores a relationship between a magnitude of the driving current, a magnitude of the power of the light, and a degree of deterioration of the light source for different cases corresponding to different degrees of deterioration; wherein the degree-of-deterioration estimation unit is configured to determine a degree of deterioration among the different degrees of deterioration that are stored in the memory that is close to the relationship between the maximum value within the predetermined period of a power of light and the maximum value within the predetermined period of the driving current; wherein the driving current peak hold unit is configured to erase the maximum value of the driving current stored within the predetermined period after the predetermined period elapses, and the optical power peak hold unit is configured to erase the maximum value of the power of the light stored within the predetermined period after the predetermined period elapses. <EOS>