A connector includes a rectangular flat-plate housing including a first positioning hole and a second positioning hole, and a contact row and a contact row held on the housing. The housing includes a first pitch side surface and a second pitch side surface on an opposite side of the first pitch side surface. The contact row and the contact row extend from the first pitch side surface to the second pitch side surface. The first positioning hole is disposed between the first pitch side surface and the contact row, and the second positioning hole is disposed between the first pitch side surface and the contact row.