An optical module 10 has a laser light source 20, optical branching means 24 for receiving laser light from the laser light source 20, making a part of the laser light pass through the optical branching means and branching a remaining part of the laser light; a photodetecting portion 30P receiving the remaining part of the laser light branched from the optical branching means 24 and a package 11 holding therein the laser light source 20, the optical branching means 24 and the photodetecting portion 30P, the package 11 having stray light reducing means 200, 201 and 202 provided therein to reduce stray light generated inside the package.