A connector assembly comprising: a first connector; and a second connector, wherein the first connector and the second connector are suitable for being fitted and electrically connected to each other, the first connector includes a first housing that houses a first connection terminal, and a protruding portion that protrudes from the first housing toward the second connector along a connector fitting direction, when the first and second connectors (5,1) are facing each other and aligned to be fitted to each other, the second connector includes a second housing that houses a second connection terminal, a cover that has a cover portion configured to cover a front surface opening of the second housing and that is provided rotatably between a first position where the cover portion covers the front surface opening and a second position where the cover portion does not cover the front surface opening, a biasing member that biases the cover to the first position, and a rotation support pin inserted into a through hole provided in a front end portion of a cover side wall of the cover, the cover is rotatably supported about a rotation axis of the rotation support pin, the rotation axis being positioned on a front projection plane of the front surface opening in front of the housing with respect to the front surface opening, the front surface opening includes an opening edge with which the cover portion contacts to cover the front surface opening, and an opening edge end portion positioned on a rear side in a direction in which the cover portion rotates from the first position toward the second position, the opening edge includes an inclined plane that intersects with the connector fitting direction and that is parallel to the rotation axis, the inclined plane intersecting at an obtuse angle with a straight line that extends from the opening edge end portion and that is orthogonal to the rotation axis, and the connector is designed to rotate the cover to the second position in response to the protruding portion pressing a pressed portion of the cover. a first connector; and a second connector, wherein the first connector and the second connector are suitable for being fitted and electrically connected to each other, the first connector includes a first housing that houses a first connection terminal, and a protruding portion that protrudes from the first housing toward the second connector along a connector fitting direction, when the first and second connectors (5,1) are facing each other and aligned to be fitted to each other, the second connector includes a second housing that houses a second connection terminal, a cover that has a cover portion configured to cover a front surface opening of the second housing and that is provided rotatably between a first position where the cover portion covers the front surface opening and a second position where the cover portion does not cover the front surface opening, a biasing member that biases the cover to the first position, and a rotation support pin inserted into a through hole provided in a front end portion of a cover side wall of the cover, the cover is rotatably supported about a rotation axis of the rotation support pin, the rotation axis being positioned on a front projection plane of the front surface opening in front of the housing with respect to the front surface opening, the front surface opening includes an opening edge with which the cover portion contacts to cover the front surface opening, and an opening edge end portion positioned on a rear side in a direction in which the cover portion rotates from the first position toward the second position, the opening edge includes an inclined plane that intersects with the connector fitting direction and that is parallel to the rotation axis, the inclined plane intersecting at an obtuse angle with a straight line that extends from the opening edge end portion and that is orthogonal to the rotation axis, and the connector is designed to rotate the cover to the second position in response to the protruding portion pressing a pressed portion of the cover.