According to an embodiment of the present disclosure, a connector that is unlikely to cause reverse insertion is provided. The connector includes a plurality of socket type connectors (1) to be mounted on a first substrate (51), and a plurality of plug type connectors (2) to be mounted on a second substrate (52). The socket type connector (1) includes a first housing (10) with a slot (19), and a plurality of contacts (8) arranged in the slot (19). The plug type connector (2) includes a second housing (20) with a header (29) to be fitted into the slot (19), and a plurality of contacts (8) arranged in the header (29). Then, the first housing (10) of the socket type connector (1) and the second housing (20) of the plug type connector (2) have a rotationally asymmetrical shape as viewed in a fitting direction.