A connector assembly comprising a connector and a mating connector, wherein: the connector is mateable with the mating connector, which is located below the connector in an upper-lower direction, along the upper-lower direction; the mating connector comprises a mating holding member and a mating lock member; the mating holding member holds the mating lock member; the mating lock member has a mating lock portion; the mating lock portion faces at least downward; the connector comprises a holding member and a lock member; the holding member has a holding portion; the lock member has a held portion, a lock portion and a coupling portion; the held portion is held by the holding portion; the lock portion and the mating lock portion are configured to lock a mated state where the connector and the mating connector are mated with each other; the coupling portion couples the held portion and the lock portion to each other; the lock portion is located below the mating lock portion and faces the mating lock portion in the upper-lower direction under the mated state; characterized in that the holding member has a stop portion, wherein the coupling portion of the lock member has an abutment portion; and when the lock portion is moved toward the held portion in a first horizontal direction perpendicular to the upper-lower direction in accordance with removal of the connector from the mating connector under the mated state, the abutment portion is brought into abutment with the stop portion so that a movement of the lock portion is restricted, wherein: the lock member has a guide projection; the guide projection projects in a second horizontal direction perpendicular to both the upper-lower direction and the first horizontal direction; the abutment portion is a part of the guide projection; the holding member is formed with a guide channel; the guide channel is recessed in the second horizontal direction and extends in the upper-lower direction; the guide channel is formed with an inner wall which intersects with the first horizontal direction; and the inner wall works as the stop portion. the connector is mateable with the mating connector, which is located below the connector in an upper-lower direction, along the upper-lower direction; the mating connector comprises a mating holding member and a mating lock member; the mating holding member holds the mating lock member; the mating lock member has a mating lock portion; the mating lock portion faces at least downward; the connector comprises a holding member and a lock member; the holding member has a holding portion; the lock member has a held portion, a lock portion and a coupling portion; the held portion is held by the holding portion; the lock portion and the mating lock portion are configured to lock a mated state where the connector and the mating connector are mated with each other; the coupling portion couples the held portion and the lock portion to each other; the lock portion is located below the mating lock portion and faces the mating lock portion in the upper-lower direction under the mated state; characterized in that the holding member has a stop portion, wherein the coupling portion of the lock member has an abutment portion; and when the lock portion is moved toward the held portion in a first horizontal direction perpendicular to the upper-lower direction in accordance with removal of the connector from the mating connector under the mated state, the abutment portion is brought into abutment with the stop portion so that a movement of the lock portion is restricted, wherein: the lock member has a guide projection; the guide projection projects in a second horizontal direction perpendicular to both the upper-lower direction and the first horizontal direction; the abutment portion is a part of the guide projection; the holding member is formed with a guide channel; the guide channel is recessed in the second horizontal direction and extends in the upper-lower direction; the guide channel is formed with an inner wall which intersects with the first horizontal direction; and the inner wall works as the stop portion. the lock member has a guide projection; the guide projection projects in a second horizontal direction perpendicular to both the upper-lower direction and the first horizontal direction; the abutment portion is a part of the guide projection; the holding member is formed with a guide channel; the guide channel is recessed in the second horizontal direction and extends in the upper-lower direction; the guide channel is formed with an inner wall which intersects with the first horizontal direction; and the inner wall works as the stop portion.