A cigarette box has a V-shaped notch (6) cut in an edge of a top wall thereof, a push-pull wall (8) forming one side wall thereof, and a fin-shaped knob (10) provided on the outer surface of the push-pull wall (8). When the push-pull wall (8) is pulled out of the cigarette box, an upper end thereof is shaped like the letter V forming a rhombic opening (12) in cooperation with the notch (6). On the other hand, when the push-pull wall (8) is pushed into the cigarette box, the upper end thereof coincides with the notch (6), forming an oppositely directed V shape and closing the opening (12).