A connector is mountable on a circuit board and connectable with a mating connector. The connector comprises a housing and a plurality of contacts which are held by the housing. The contacts form two or more contact rows. The contacts of each of the contact rows are arranged in a pitch direction. Each of the contacts has a fixed portion which is fixed to the circuit board when the connector is mounted on the circuit board. The housing has one or more openings each of which is positioned between neighboring two of the contact rows in a predetermined direction perpendicular to the pitch direction. Two or more of the fixed portions extend into one of the openings.