A detecting member 40 is attached within a female electrical connector housing 20 in a manner whereby it is capable of moving in a width-wise direction. A contacting face 47 of a detecting protrusion 46 of a detecting arm 45 makes contact with a locking arm 26 when this locking arm 16 is in a free state prior to two housings 10 and 20 being fitted together, this contact regulating the movement of the detecting member 40. When the two housings 10 an 20 are being fitted together, the contact face 47 of the stopper arm 45, and a side face 53 of a main body 41 make contact with a side face 51 of the bent locking arm 26, thereby regulating the movement of the detecting member 40. After correct fitting is completed, the locking arm 26 returns to its original position. Consequently, the contacting state of the stopper arm 45 and the main body 41 with the side face 51 is released, thereby allowing the detecting member 40 to be moved to a position indicating correct fitting of the housings 10, 20.