To open and close a projected window provided at a high altitude merely by operating a single operation member.

This opening and closing device includes a forwardly and reversely rotatable pulley 12, the operation member 13 for rotating the pulley 12 in one direction by a pulling operation, a gear 10 interlocking to the pulley 12, a rotating body 9 interlocking to the gear 10, a means (power spring 11) for biasing at least one of the pulley 12, the gear 10, and the rotating body 9 in the direction in which a sliding screen is opened, and a lock means (pulley lock 15) for restraining the rotation of at least one of the pulley 12, the gear 10, and the rotating body 9 when the sliding screen is fully closed. The rotating body 9 is connected to the operating mechanism of the sliding screen in such a manner as to open and close the sliding screen 2 when the rotating body 9 is rotated, moves the sliding screen 2 to the full close position by rotating the operation member 13 with the pulling operation, and starts the sliding screen 2 to the full open position by rotating with the biasing means when the lock means is released.