A slide member includes a side edge holding part, which extends towards the front end edge of the housing, and a front end holding part, which is connected to the front end of the side edge holding part and extends in the transverse direction of the housing. The slide member is able to slide forward and backward along one side edge of the bottom wall part of the housing. The housing contains a mistaken insertion prevention convex part which the front end or rear end of a mistakenly inserted card contacts.