An optical module is configured being provided with: a first case fixed to an implementation surface of an implementation substrate to cover an LD and an LD driver； a first filler filled in the first case to seal the LD and the LD driver； a second case fixed to the implementation surface of the implementation substrate to cover the first case in a state of not adhering to the first case； a third case accommodating the implementation substrate and the second case inside； and a second filler filled in the third case to seal the implementation substrate and the second case.
