A manifold connected to a solenoid-operated valve which has a connector having a plurality of fluid passages for supplying and discharging a fluid under pressure to and from the solenoid-operated valve, includes a body having a substantially rectangular shape, an engaging groove defined in an upper surface of the body, a mount hole defined in the body, and a stopper member. The stopper member is inserted in the mount hole, and has an end retained in the mount hole. The stopper member has an extensible resilient spring arm and an engaging hole defined in the stopper member for receiving and engaging the connector of the solenoid-operated valve when the stopper member is displaced.