A connector, comprising: at least one terminal fitting formed with a contact portion with a mating terminal at or near a front end portion; a housing formed with at least one cavity into which the terminal fitting is to be at least partly inserted in an insertion direction, at least one locking lance formed to substantially extend forward in a cantilever manner along an inner wall of the cavity, normally located at a locking position where the locking lance can lock the terminal fitting in a retained state and resiliently deformable to an unlocking position where the locking lance is disengaged from the terminal fitting; at least one deformation space formed in the housing to allow resilient deformation of the locking lance toward the unlocking position; and a front retainer including at least one deformation restricting portion projecting substantially along the inserting direction and movable between a restricting position (ResP) and a retracted position (RetP) in a state where the front retainer is mounted to the housing from front, wherein: the deformation restricting portion at least partly enters the deformation space to restrict the resilient deformation of the locking lance with the front retainer located at the restricting position (ResP) while being substantially retracted forward of the deformation space to allow the resilient deformation of the locking lance with the front retainer located at the retracted position (RetP); the locking lance is resiliently deformed from the locking position to the unlocking position by an unlocking operation by an unlocking jig to be at least partly inserted into the housing from the outside with the front retainer located at the retracted position (RetP); the housing is formed with at least one jig insertion hole penetrating through an outer wall portion located at a side of the deformation space substantially opposite to the locking lance; and the deformation restricting portion is formed with at least one guide portion which allows the unlocking jig inserted through the jig insertion hole to reach the locking lance with the front retainer located at the retracted position (RetP) and/or substantially positions the unlocking jig in a width direction crossing both a resiliently deforming direction of the locking lance and an inserting direction of the terminal fitting into the cavity; characterized in that the deformation restricting portion is formed with at least one closing portion for at least partly closing the jig insertion hole with the front retainer located at the restricting position (ResP). at least one terminal fitting formed with a contact portion with a mating terminal at or near a front end portion; a housing formed with at least one cavity into which the terminal fitting is to be at least partly inserted in an insertion direction, at least one locking lance formed to substantially extend forward in a cantilever manner along an inner wall of the cavity, normally located at a locking position where the locking lance can lock the terminal fitting in a retained state and resiliently deformable to an unlocking position where the locking lance is disengaged from the terminal fitting; at least one deformation space formed in the housing to allow resilient deformation of the locking lance toward the unlocking position; and a front retainer including at least one deformation restricting portion projecting substantially along the inserting direction and movable between a restricting position (ResP) and a retracted position (RetP) in a state where the front retainer is mounted to the housing from front, the deformation restricting portion at least partly enters the deformation space to restrict the resilient deformation of the locking lance with the front retainer located at the restricting position (ResP) while being substantially retracted forward of the deformation space to allow the resilient deformation of the locking lance with the front retainer located at the retracted position (RetP); the locking lance is resiliently deformed from the locking position to the unlocking position by an unlocking operation by an unlocking jig to be at least partly inserted into the housing from the outside with the front retainer located at the retracted position (RetP); the housing is formed with at least one jig insertion hole penetrating through an outer wall portion located at a side of the deformation space substantially opposite to the locking lance; and the deformation restricting portion is formed with at least one guide portion which allows the unlocking jig inserted through the jig insertion hole to reach the locking lance with the front retainer located at the retracted position (RetP) and/or substantially positions the unlocking jig in a width direction crossing both a resiliently deforming direction of the locking lance and an inserting direction of the terminal fitting into the cavity; characterized in that the deformation restricting portion is formed with at least one closing portion for at least partly closing the jig insertion hole with the front retainer located at the restricting position (ResP).