For connection and disconnection of both connectors with ease and assurance in a narrow work space and connection, and for disconnection of a safety circuit unit without mistakes and in a saved-space, a low-insertion-force connector assembly 53 is provided with one connector receiving the one terminal and other connector 27 receiving a mating terminal, wherein the one connector includes a driving lever 6 having a rotative circular-arc-shaped gear part 13, and, pivotally supported along a wall part 17 of the one connector, a gear wheel part 11 engaged with the gear part, and a gear member 4 having a spiral groove engaged with a driven projection 37 of the other connector, wherein the safety circuit unit 8 is slidably disposed in the one connector, a small connector 38 for connection is disposed in the other connector, thereby the driving lever 6, at a provisional position, prevents the safety circuit unit from rotating in a connecting direction of the safety circuit unit, and, at a connecting position, allows the safety circuit unit to move and is blocked to rotate by a flange 31.