An opening/closing direction restriction mechanism for a manual shutter device which is configured by a fixed shaft substantially horizontally extended, a winding member rotatably disposed on the fixed shaft to wind a slat, and a torsion spring disposed inside the winding member to bias the winding member in a winding direction which winds the slat, comprising:
- a bracket attached to one of the winding member and the fixed shaft;
- a flange disposed adjacent to the bracket and attached to the other of the winding member and the fixed shaft;
- and
- a two-way clutch disposed on an opposing surface facing the flange of the bracket, wherein
- a gear formed on the flange and an external gear for clutch disposed on an input shaft of the two-way clutch are engageably disposed,
- the two-way clutch is disposed such that a reverse rotation inhibited state in which the external gear for clutch is allowed to be rotated along a winding direction of the winding member and the external gear for clutch is inhibited from being rotated along an unwinding direction and a forward rotation inhibited state in which the external gear for clutch is inhibited from being rotated in the winding direction of the winding member and the external gear for clutch is allowed to be rotated along the unwinding direction can be switched.