To solve the problem that a conventional electric curtain rail is a device which is complicated in structure and heavy and which requires a skilled technique to install.

One small motor is used as a geared motor so that a cord can be pulled and turned normally and inversely in one direction and in both directions utilizing a door roller. In the case of one direction, three door rollers are used. In both directions, seven door rollers are used. Then, the cord for two rotations or more is wound on the door roller to apply force equally. Thus, the code is prevented from slipping on the door roller and force from a drive shaft is transmitted without waste. Thus, a large pulling force is successfully generated from small force. Since the electric curtain rail device is light in weight and simple in structure so that the device is easy to install and requires no skilled technique.