A connector includes a holder (10) having a peripheral wall (11) open on opposite first and second ends. A first housing (21) is assembled in the peripheral wall (11) from the first end of the holder (10), a second housing (40) is connected to the first housing (21) from the second end of the holder (10). Stoppers (20) are formed on the peripheral wall (11) and resilient contact pieces (28) are formed on the first housing (21). The resilient contact pieces (28) are deflected by interference with the stoppers (20) in the process of assembling the first housing (21) into the peripheral wall (11). The resilient contact pieces (28) are locked to the stoppers (20) to regulate detachment of the first housing (21) from the peripheral wall (11) toward the first end in the process of assembling the first and second housings (21, 40).