The connector includes a rear holder inserted into an opening 10 of a connector housing for locking terminals. The holder has a locking portion engaging with a rear end edge of the opening. The locking portion is formed with an inclined stopping surface. The stopping surface is facing in a disengaging direction of the holder and is capable of making a sliding contact with the rear end edge of the opening. The locking portion is a locking projection or may be an inclined stopping surface formed in a rear end portion of the holder. The holder has a base plate, a terminal locking projection, and a pair of side plates. The side plate is formed with a preliminary engagement portion associated with a preliminary locking portion of the connector housing. On final locking of the holder, the fore end face of the rear wall positioned behind the opening of the connector housing abuts against the rear end surface of the base plate of the holder.