A surface mount connector comprising: a box-shaped electrically insulating substrate side housing with an opening on one side, the substrate side housing including a rectangular terminal mount wall, and four side walls (16, 18, 20, 22) standing from respective four sides of the terminal mount wall; a plurality of electrically conductive terminals (30, 32, 34, 36) provided on the terminal mount wall; and a plug connector including a plug housing configured to be detachably inserted into the substrate housing, wherein the substrate side housing is capable of being mounted on a printed board such that the surface mount connector is used either in a straight mounting form in which the opening opens upwards from the printed board, or in a right-angle mounting form in which the opening opens sideways with respect to the printed board, wherein the terminal mount wall is a wall extending in a plane defined by mutually orthogonal X and Y axes, wherein the terminals (30, 32, 34, 36) are arranged in two rows, the rows being apart from each other in an X axis direction, such that the terminals (30, 32, 34, 36) in each row are in alignment with one another in a Y axis direction, wherein the four side walls (16, 18, 20, 22) of the substrate side housing consist of two first side walls (16, 18) which are separated from each other in the X axis direction, and two second side walls (20, 22) which are separated from each other in the Y axis direction, wherein a lock part is provided on one of the two first side walls (16, 18) for detachably locking the plug housing in an inserted position, wherein, on each of the second side walls (20, 22), a first reinforcement plate mount part and a second reinforcement plate mount part are provided at two different positions apart from each other in the X axis direction, and a reinforcement plate is allowed to each of the two first and the two second reinforcement plate mount parts (46, 48), and wherein the reinforcement plates mounted to the two first reinforcement plate mount parts and/or the two second reinforcement plate mount parts have respective outer edges which are configured to abut and be fixed to the printed board; characterized in that the first and second reinforcement plate mount parts (46, 48) extend in parallel with each other on an outer surface of each of the second side walls (20, 22) and wherein each reinforcement plate has a width of approximately half the size of outer surfaces of the second side walls (20, 22) in the X axis direction. a box-shaped electrically insulating substrate side housing with an opening on one side, the substrate side housing including a rectangular terminal mount wall, and four side walls (16, 18, 20, 22) standing from respective four sides of the terminal mount wall; a plurality of electrically conductive terminals (30, 32, 34, 36) provided on the terminal mount wall; and a plug connector including a plug housing configured to be detachably inserted into the substrate housing, wherein the substrate side housing is capable of being mounted on a printed board such that the surface mount connector is used either in a straight mounting form in which the opening opens upwards from the printed board, or in a right-angle mounting form in which the opening opens sideways with respect to the printed board, wherein the terminal mount wall is a wall extending in a plane defined by mutually orthogonal X and Y axes, wherein the terminals (30, 32, 34, 36) are arranged in two rows, the rows being apart from each other in an X axis direction, such that the terminals (30, 32, 34, 36) in each row are in alignment with one another in a Y axis direction, wherein the four side walls (16, 18, 20, 22) of the substrate side housing consist of two first side walls (16, 18) which are separated from each other in the X axis direction, and two second side walls (20, 22) which are separated from each other in the Y axis direction, wherein a lock part is provided on one of the two first side walls (16, 18) for detachably locking the plug housing in an inserted position, wherein, on each of the second side walls (20, 22), a first reinforcement plate mount part and a second reinforcement plate mount part are provided at two different positions apart from each other in the X axis direction, and a reinforcement plate is allowed to each of the two first and the two second reinforcement plate mount parts (46, 48), and wherein the reinforcement plates mounted to the two first reinforcement plate mount parts and/or the two second reinforcement plate mount parts have respective outer edges which are configured to abut and be fixed to the printed board; characterized in that the first and second reinforcement plate mount parts (46, 48) extend in parallel with each other on an outer surface of each of the second side walls (20, 22) and wherein each reinforcement plate has a width of approximately half the size of outer surfaces of the second side walls (20, 22) in the X axis direction.