A connector device comprising: a first connector that includes a first terminal; a second connector that includes a second terminal to which the first terminal is electrically connected; a movable arm that is provided on the first connector and configured to hold the second connector in a fitted state with respect to the first connector; a connector fitting assurance mechanism that locks the movable arm by slidably engaging a slider with the movable arm that holds the second connector in the fitted state; a signal circuit that is configured to be possible to electrically connect a first electric wire connected to the first terminal and a second electric wire connected to the second terminal to each other; and an interlock terminal that is provided in the slider and configured to close the signal circuit when the movable arm is locked and to open the signal circuit when the movable arm is not locked, wherein the slider is disposed at a position where a rear end portion of the slider projects backward from a rear end of the first connector when the movable arm is not locked, and is disposed at a position where the rear end of the first connector and the rear end portion of the slider are substantially flush with each other when the movable arm is locked, characterised in that wherein a rear holder is attached to the rear end of the first connector to restrict a seal member from a separation, the sealing member being attached to an opening leading out the first electric wire of a terminal accommodation chamber in which the first terminal is accommodated, wherein a rear end surface of the rear holder is provided with a notch configured to be cut out, such that the rear end portion of the slider is inserted and wherein the rear end portion of the slider is disposed at a position substantially flush with the rear end surface of the rear holder when the movable arm is locked. a first connector that includes a first terminal; a second connector that includes a second terminal to which the first terminal is electrically connected; a movable arm that is provided on the first connector and configured to hold the second connector in a fitted state with respect to the first connector; a connector fitting assurance mechanism that locks the movable arm by slidably engaging a slider with the movable arm that holds the second connector in the fitted state; a signal circuit that is configured to be possible to electrically connect a first electric wire connected to the first terminal and a second electric wire connected to the second terminal to each other; and an interlock terminal that is provided in the slider and configured to close the signal circuit when the movable arm is locked and to open the signal circuit when the movable arm is not locked, wherein the slider is disposed at a position where a rear end portion of the slider projects backward from a rear end of the first connector when the movable arm is not locked, and is disposed at a position where the rear end of the first connector and the rear end portion of the slider are substantially flush with each other when the movable arm is locked, characterised in that wherein a rear holder is attached to the rear end of the first connector to restrict a seal member from a separation, the sealing member being attached to an opening leading out the first electric wire of a terminal accommodation chamber in which the first terminal is accommodated, wherein a rear end surface of the rear holder is provided with a notch configured to be cut out, such that the rear end portion of the slider is inserted and wherein the rear end portion of the slider is disposed at a position substantially flush with the rear end surface of the rear holder when the movable arm is locked.