A blade open-close device includes a blade for which an open or closed state is easily viewable from outside. A blade open-close device includes a base having a base opening, and a cover covering the base and having a cover opening adjacent to the base opening in the base in Z-direction. The blade open-close device further includes a blade movable in X-direction in a blade chamber between the base and the cover and including a light emitter that emits light, and an actuator that moves the blade to a closing position to expose at least part of the light emitter in the blade through the cover opening and retracts the blade to an opening position to allow the cover opening and the base opening to communicate with each other.