A laser transmitter device includes a laser light source, first and second optical elements, and first and second detection elements. The first optical element has a first optical characteristic with wavelength dependency, whose light transmissivity or reflectivity shows a monotone increase or decrease within a wavelength range over channels. The second optical element has a second optical characteristic with wavelength dependency, whose transmissivity or reflectivity changes in a cycle corresponding to intervals of the channels or two times the intervals. The first detection element detects an intensity of light emitted from the laser light source and coming via the first optical element, and generates a first electric signal reflecting the first optical characteristic. The second detection element detects an intensity of light emitted from the laser light source and coming via the second optical element, and generates a second electric signal reflecting the second optical characteristic.