A connector which is capable of preventing degradation of transmission, and achieving downsizing. Contact portions of first and second signal contacts, and contact portions of ground contacts are arranged in a row in a contact arranging direction. Contact portions of contacts for non-high-speed transmission are arranged in a row in the contact arranging direction. The row formed by the contact portions of the first and second signal contacts, and the contact portions of the ground contacts, and the rows formed by the contact portions of the contacts for non-high-speed transmission are parallel. The contact portions of each pair of first and second signal contacts are disposed between the contact portions of adjacent ones of the ground contacts in the contact arranging direction.