A connector (S) includes a housing (10) having an insertion hole (16) formed through three adjacent surfaces of the housings (10) and communicating with cavities (11). A retainer (50) is inserted into the insertion hole (16) through an insertion port (16A) in a first of the three adjacent surfaces of the housing (10) and locks terminal fittings (98). A front holder (30) is mounted on the housing (10) from a front end thereof and has side panels (32A) that cover portions of the insertion hole (16) in the second and third surfaces while leaving the insertion port (16A) open. The retainer (50) slides on inner surfaces of the side panels (32A) of the front holder (30).
