A connector comprising: a plurality of terminal fittings (10, 110, 210) attached each to a terminal of an electric wire (We); a housing (20, 120) that houses the plurality of the terminal fittings (10, 110, 210) at a housing complete position in a terminal housing room on an inner side and that is configured to be inserted into and engaged with a counterpart engagement part from an end along an inserting direction; and a terminal retaining member (50, 150, 250) that is assembled to the housing (20, 120) from outside along an assembling direction orthogonal to the inserting direction and, at an assembling complete position to the housing (20, 120), retains the plurality of the terminal fittings (10, 110, 210) remaining at the housing complete position, wherein each of the plurality of the terminal fittings (10, 110, 210) includes a penetration hole (13, 113), the terminal retaining member (50, 150, 250) includes a retaining protrusion (52, 152, 252) that is, at the assembling complete position, inserted into the penetration hole (13, 113) at the housing complete position, and retains the plurality of the terminal fittings (10, 110, 210) at the housing complete position while the plurality of the terminal fittings, 110, 210 remains at that position, characterized in that the penetration hole is formed to have a left-right asymmetric shape including a first hole part that is arranged on a left side in a terminal left-right direction orthogonal to the inserting direction and the assembling direction, and a second hole part that has a shape different from a shape of the first hole part and is arranged on a right side of the first hole part in the terminal left-right direction, and in that the retaining protrusion is formed to have a left-right asymmetric shape including a first protrusion part that is arranged on the left side in the terminal left-right direction and is, at the assembling complete position, fitted into the first hole part at the housing complete position, and a second protrusion part that has a shape different from a shape of the first protrusion part, is arranged on the right side of the first protrusion part in the terminal left-right direction, and is, at the assembling complete position, fitted into the second hole part at the housing complete position. a plurality of terminal fittings (10, 110, 210) attached each to a terminal of an electric wire (We); a housing (20, 120) that houses the plurality of the terminal fittings (10, 110, 210) at a housing complete position in a terminal housing room on an inner side and that is configured to be inserted into and engaged with a counterpart engagement part from an end along an inserting direction; and a terminal retaining member (50, 150, 250) that is assembled to the housing (20, 120) from outside along an assembling direction orthogonal to the inserting direction and, at an assembling complete position to the housing (20, 120), retains the plurality of the terminal fittings (10, 110, 210) remaining at the housing complete position, wherein each of the plurality of the terminal fittings (10, 110, 210) includes a penetration hole (13, 113), the terminal retaining member (50, 150, 250) includes a retaining protrusion (52, 152, 252) that is, at the assembling complete position, inserted into the penetration hole (13, 113) at the housing complete position, and retains the plurality of the terminal fittings (10, 110, 210) at the housing complete position while the plurality of the terminal fittings, 110, 210 remains at that position, characterized in that the penetration hole is formed to have a left-right asymmetric shape including a first hole part that is arranged on a left side in a terminal left-right direction orthogonal to the inserting direction and the assembling direction, and a second hole part that has a shape different from a shape of the first hole part and is arranged on a right side of the first hole part in the terminal left-right direction, and in that the retaining protrusion is formed to have a left-right asymmetric shape including a first protrusion part that is arranged on the left side in the terminal left-right direction and is, at the assembling complete position, fitted into the first hole part at the housing complete position, and a second protrusion part that has a shape different from a shape of the first protrusion part, is arranged on the right side of the first protrusion part in the terminal left-right direction, and is, at the assembling complete position, fitted into the second hole part at the housing complete position.