An optical transmission module includes: a bias current drive circuit to drive a bias current of a light-emitting element, on a basis of an input bias current setting value; a modulation current drive circuit to drive a modulation current of the light-emitting element, on a basis of an input modulation current setting value; a light-receiving element to measure an optical output power of the light-emitting element; a determiner to determine whether a difference between a target value of the optical output power and the optical output power measured by the light-receiving element is equal to or more than a threshold; and a controller configured to perform a correction control to the bias current drive circuit so that the bias current is reduced in accordance with the difference, when it is determined that the difference is equal to or more than the threshold by the determiner.