In a package (5) formed by a supporting portion (5a) for supporting a light emitting portion (7) or a light receiving portion (9) for emitting or receiving an optical signal, and a lid (5b) for covering the supporting portion (5a); the supporting portion (5a) or the lid (5b) includes a light guide mounting surface (22) for supporting at least one end including an incident/exit port of the optical signal in a film light guide (4) for optically coupling with the light emitting portion (7) or the light receiving portion (9) and transmitting the optical signal; and a length (D) in a Z-direction serving as a perpendicular direction with respect to the light guide mounting surface (22) from the light guide mounting surface (22) of the supporting portion (5a) or the lid (5b) to the lid (5b) or the supporting portion (5a) facing the light guide mounting surface (22) is longer than a length (d) in the Z-direction in a region of the film light guide (4) supported by the light guide mounting surface (22). The light guide package having a structure in which the deformation and the damage of the core are less likely to occur even when subjected to impact by vibration and the like is thereby provided.