An external resonance type laser module includes a quantum cascade laser, a MEMS diffraction grating configured to include a diffraction/reflection portion configured to diffract and reflect light emitted from the quantum cascade laser and return a part of the light to the quantum cascade laser by swinging the diffraction/reflection portion, and a controller configured to control driving of the quantum cascade laser. The controller is configured to pulse-drive the quantum cascade laser such that pulsed light of a second frequency higher than a first frequency at which the diffraction/reflection portion swings is emitted from the quantum cascade laser and a phase of the pulsed light changes each time the diffraction/reflection portion reciprocates m times (m: an integer of 1 or more).