Abstract: A housing main body (20) is connectable with a mating male connector (M) and internally formed with an accommodating chamber (22) into which an auxiliary housing (30) can be accommodated. The housing main body (20) is formed with cavities (23) for accommodating female terminal fittings (40) electrically connectable with mating male terminal fittings (11), and the respective cavities (23) are arranged at positions symmetrical with respect to an axis of symmetry (L1). A lock arm (50) is disposed on the axis of symmetry (L1) of the respective cavities (23). The housing main body (20) is integrally formed with the lock arm (50) capable of holding the male connector (M) connected by the engagement with an engaging portion (16) of the male connector (M).