Abstract: A pull cord stopper device (20) for use in a blind apparatus operative in response only to a cord control string attached to pull cords. The pull cord stopper device (20) is disposed in a head box (10) and is adaptive to a large-scale blind apparatus. A stopper case (28) of the pull cord stopper device (20) comprises a comb portion (40) for separating the pull cords (16), a knurled portion (42) for guiding a pinch roller (30), and a pin (54) received in a guide groove (52) formed in a switch member(34), for guiding the movement of the switch member (34). A slidable block (32) rotatably supports the pinch roller (30), and is operative to move within the stopper case (28) in the direction of movement of the pull cords (16) as a result of a rotation of the pinch roller (30).