A laser module includes a semiconductor laser element and a feedback optical component forming an external cavity with the semiconductor laser element. Even if a ratio of a current threshold of the laser module changing according to a polarized state of returned light from the feedback optical component to a current threshold of the semiconductor laser element is in an arbitrary range within a predetermined range, a total value of a relative intensity noise occurring between a first frequency determined according to a cavity length of the external cavity and at least equal to or more than a frequency band of using a laser light and a second frequency calculated by multiplying the first frequency by a predetermined number is equal to or more than -40 dB.