A second connector housing 20 to be fitted into a first connector housing 10 is equipped with a first housing 21 which holds second terminal metal fittings belonging to a first group and a second housing 22 integrally formed with the first housing 21. The second housing 22 holds second terminal metal fittings belonging to a second group. The second housing 22 is connected slidably to a portion located on the one side of the first housing 21 so that during a manipulation for fitting the second connector housing 20 into the first connector housing 10 fitting of the second terminal metal fittings belonging to the second group with corresponding ones of the first terminal metal fittings is completed earlier than fitting of the second terminal metal fittings belonging to the first group.