According to the USB 2.0 standard, it is limited to 5 m.
In fact, cables that exceed this are sold by major manufacturers.
(It is said that up to about 10 m, it does not affect the communication speed much.) 

Not only extension cables, but also the following are also sold.
It is a “USB cable with repeater function”. (It is also called an active cable.) 


It is sold by multiple companies, but the product in the photo is
This is Sanwa Supply Co., Ltd.’s KB-USB-R212 [12m Extension USB Active Repeater Cable].




According to the USB cable standard, the maximum length of the cable is 5 m between devices.
However, by using this “USB cable with repeater function”, you can connect devices with a cable of 5 m or more.
For the product in the picture, this cable alone can be extended by 12m.


This cable has a built-in signal amplification correction circuit. By restoring the attenuated signal in this circuit, it is possible to extend the cable.
The cable can also be extended to more than 12 meters. In that case, wire as follows.




I connected a 12m USB cable with repeater function (product in the photo) and the cable included with the camera (1 .8m) to our USB camera, and it worked without problems. However, in the instruction manual of the USB cable with repeater function (product in the photo), there was a sentence that said, “In order to ensure stable operation and recognition, it is recommended that the USB device to be connected is a device that operates on its own power.”
Of course, there are also active cables that use USB power (bus-powered).
It is easy to use without the need for a power supply. However, if your PC’s power supply is vulnerable, it can become unstable.


If the USB cable is extended, a voltage drop will occur, so it is recommended that devices (including our USB cameras) that operate by power supply from a PC be sure to check the operation before using it.