An optical module having a high-moisture-proof package structure in which dew condensation does not occur is provided.An optical module includes optical components including a light source, a pedestal on which the optical components are mounted, a cover which is combined to the pedestal to seal the optical components, and an emitting window disposed in the cover to take light from the light source outside. The pedestal and the cover are sealed with an O ring and a liquid seal material such that a compression direction of the O ring and a compression direction of the liquid seal material are almost perpendicular to each other.