A male connector (10) to be covered together with a board (P) by a case (C) with the male connector (10) connected to the board (P). The male connector (10) includes a male housing (11) connectable to a female connector (60) and including a back wall (25A) partitioning between the outside of the case (C) on the side of the female connector (60) and the inside of the case (C) on the side of the board (P) while extending in a vertical direction. The back wall (25A) has an opening (26) open in a connecting direction of the female connector (60) and allowing communication between the outside and inside of the case (C). A step is provided on an edge of the opening (26) so that an upper edge (26A) of the opening (26) is more forward than a lower edge (26B) of the opening (26).