To provide a curtain opening/closing device whose installation space is reduced, and which can open/close a curtain along a curved or inclined route as well.

The curtain opening/closing device 10 is provided with a guide rail 11 having a passage 17 on an upper side, a passage 16 on a lower side and a running path 16a, a bead string body 12 freely slidably provided inside the upper and lower passages 16 and 17 of the guide rail and capable of transmitting pushing and pulling force, a driving wheel 43 for driving the bead string body back and forth and a carrier 18 provided on the tip of the bead string body 12, to which the tip part of the curtain 20 is attached. The bead string body 12 is composed of a flexible wire 15 and many beads 14 provided around the wire 15 and the driving wheel 43 is engaged with the beads 14 of the bead string body and drives them to travel back and forth.