An automatic open-close device for use with a fitting, the device may include a rack secured to the fitting; a pinion structured to mesh with the rack; a turn-driving mechanism structured to drive the pinion to turn; and a holding member structured to rotatably hold the pinion. The holding member may be movable between a meshing position in which the rack and the pinion are engaged and a disengaging position in which the rack and the pinion are disengaged. The rack and the pinion may be configured such that, when the holding member is in the meshing position and the driving mechanism drives the pinion to turn, the fitting opens and closes.