A laser device includes a first optical comb laser, a second optical comb laser having a repetition frequency different from the first optical comb laser, a detection unit that detects interfering light between light output from the first optical comb laser and light output from the second optical comb laser and a control circuit. The control circuit controls at least one of a first CEO frequency, which is a carrier-envelope offset frequency of the first optical comb laser, or a second CEO frequency, which is a carrier-envelope offset frequency of the second optical comb laser, on the basis of output of the detection unit and thus changes a difference frequency, which is a difference between the first CEO frequency and the second CEO frequency.