A light guide device is provided. The light guide device includes a light guide member and a reflective member. The light guide member includes a junction surface, a first light incident member, a second light incident member, a contact surface, and a reflective curve surface. The reflective member includes a reflective surface adapted to the reflective curved surface and the contact surface of the light guide member. The first light receiving member and the second light receiving member respectively aligned to a first light-emitting element and a second light-emitting element, and are used to receive light emitted by the first light-emitting element and the second light-emitting element and guide the received light out.