A housing (10) includes locking portions (13) on both sides of a mounting surface (12). A fixing member (60) includes a housing mounting portion (61) to be arranged along the mounting surface (12) in the housing (10) and locked by the locking portions (13). A plurality of ribs (18) arranged while being spaced apart in a first direction (front-back direction) along the mounting surface (12) and respectively extending in a second direction (vertical direction) intersecting with the first direction are provided on the mounting surface (12) of the housing (10). The housing mounting portion (61) of the fixing member (60) is provided with a plurality of grooves (69) extending in the second direction and to be fit to the respective ribs (18).