In order to achieve a reduction in material costs and a sufficient locking strength at the same time by using a reinforcement plate commonly usable for connectors in different forms, a connector includes: a box-shaped substrate side housing 12 containing a terminal mount wall 14 extending in a plane defined by mutually orthogonal X and Y axes and four side walls 16, 18, 20, 22; and terminals 30, 32, 34, 36 arranged in two rows, the rows being apart from each other in an X axis direction, such that the terminals in each row are in alignment with one another in a Y axis direction, wherein the four side walls 16, 18, 20, 22 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 60 is provided on one of the two first side walls 16, 18 for detachably locking a plug housing 72 in an inserted position, wherein, on each of the second side walls 20, 22, a first reinforcement plate mount part 46 and a second reinforcement plate mount part 48 are provided at two different positions apart from each other in the X axis direction, and a reinforcement plate 62 is allowed to be mounted to each of the two first and the two second reinforcement plate mount parts 46, 48, and wherein the reinforcement plates 62 mounted to the first reinforcement plate mount parts 46 and/or the second reinforcement plate mount parts 48 have respective outer edges which abut and are fixed to the printed board 100.