To provide an external curtain opening/closing device which does not require wiring work for opening a through-hole for passing a power line in a wall or the like.

The external curtain opening/closing device which is fitted outside a glass window 3 to open/close a curtain covering the glass panel 3a is provided with: a winding drive mechanism which is fitted outside the glass window 3 and winds up and houses the curtain; and a power supply mechanism 6 for supplying power to the winding drive mechanism. The power supply mechanism 6 includes: an inward power transmission coil 7 which is disposed inside the glass panel 3a and generates an AC magnetic field; and an outside power receiving coil 8 which is disposed outside the glass panel 3a, connected to the winding drive mechanism, and supplies power generated by electromagnetic induction by the AC magnetic field to the winding drive mechanism.