A connector (11, 21) configured to be mounted on a mounting object and configured to be connected to a counter connector (21, 11), the connector comprising: a housing (31, 51); and a plurality of contacts (41, 61) retained by the housing, wherein the plurality of contacts form a plurality of contact arrays (S1-S4, T1-T4) that linearly extend in a predetermined array direction in parallel to each other, wherein each of the plurality of contacts has a mounting portion (41A, 61A) that is configured to be fixed to the mounting object when the connector is mounted on the mounting object and a contact portion (41B, 61B) that is configured to contact a corresponding contact of the counter connector when the connector is connected to the counter connector, wherein the mounting portions of contacts constituting at least two contact arrays adjacent to each other of the plurality of contact arrays extend in a same elongation direction, wherein the housing (31, 51) has an opening portion (36A, 36B, 56A, 56B) formed between the at least two contact arrays and extending in the predetermined array direction, wherein the mounting portions of contacts constituting one contact array of two contact arrays situated on opposite sides across the opening portion protrude in the opening portion and the mounting portions of the contacts constituting another one contact array of the two contact arrays protrude from an end of the housing, characterised in that the contacts constituting each contact array of the at least two contact arrays are disposed in a position other than a position where those contacts completely coincide with contacts constituting another contact array of the at least two contact arrays in a direction perpendicular to the predetermined array direction. a housing (31, 51); and a plurality of contacts (41, 61) retained by the housing, wherein the plurality of contacts form a plurality of contact arrays (S1-S4, T1-T4) that linearly extend in a predetermined array direction in parallel to each other, wherein each of the plurality of contacts has a mounting portion (41A, 61A) that is configured to be fixed to the mounting object when the connector is mounted on the mounting object and a contact portion (41B, 61B) that is configured to contact a corresponding contact of the counter connector when the connector is connected to the counter connector, wherein the mounting portions of contacts constituting at least two contact arrays adjacent to each other of the plurality of contact arrays extend in a same elongation direction, wherein the housing (31, 51) has an opening portion (36A, 36B, 56A, 56B) formed between the at least two contact arrays and extending in the predetermined array direction, wherein the mounting portions of contacts constituting one contact array of two contact arrays situated on opposite sides across the opening portion protrude in the opening portion and the mounting portions of the contacts constituting another one contact array of the two contact arrays protrude from an end of the housing, characterised in that the contacts constituting each contact array of the at least two contact arrays are disposed in a position other than a position where those contacts completely coincide with contacts constituting another contact array of the at least two contact arrays in a direction perpendicular to the predetermined array direction.