A connector unit has a male connector that includes a cylindrical proximal portion in which a female terminal is accommodated, and a female connector that includes a tubular proximal portion in which a male terminal is held. The cylindrical proximal portion has a cylinder side marking portion including a flat surface formed on a part of an outer circumferential surface thereof, and a cylinder side rotation restricting portion including a groove portion or a projecting portion formed on the outer circumferential surface thereof. The tubular proximal portion has a tube side marking portion including a flat surface formed on an inner surface circumferential surface of the tubular proximal portion, and a tube side rotation restricting portion including a projecting portion projected from the inner circumferential surface or a groove portion formed in the inner circumferential surface.