PURPOSE: To permit an opening and closing device to be simply operated for a gate door of a width enough to come in and out with a margin and also to set it easily by using an opening and closing device consisting of a looped runner, a driver for the runner, and a connector for them with a gate door.

CONSTITUTION: A hole pipe 6 is placed between both gate poles 4 above both gate doors 1 and rails 5 are welded to the downside of the pipe 6. On both edges of the pipe 6, a driver 8 having a motor to operate a chain 9 for opening or closing the gate door 1 laterally is provided. A connector 12 to be bilaterally opened or closed, together with a running bar hanging the central hang lever 2a as the chain 9 moves, is attached to a part of the lower side chain 9. Setting and removing can thus be easily made.