Abstract: An optical module package is provided, the optical module package including a housing main body, a cover body, first and second holding members, and a fiber unit. The first and second holding members may form, inside thereof, a unit accommodating part according to the outer size of a fiber unit in a direct opposing state. The housing main body has locking projections set an arrangement interval between two opposing surfaces of outer surface of the first and second holding members arranged to oppose each other, and a space sandwiched between locking projections is set as an accommodating space for the first and second holding members.