Provided is an optical transmitter module. The optical transmitter module includes a package including a lower substrate and a side substrate in which a through hole is formed, and a feed-through block coupled to the side substrate in which the through hole is formed. The feed-through block includes a feed-through substrate, at least one lead pin penetrating the feed-through substrate and coupled to the feed-through substrate, a base substrate formed to extend from the feed-through substrate in a direction in which the at least one lead pin is coupled, and a dielectric substrate formed between the at least one lead pin and the base substrate protruding from the feed-through substrate. Therefore, it is possible to improve the quality of a signal transmitted by the optical transmitter module.