A roller shutter comprises a support, a rolling drum rotatably arranged on the support and provided with a curtain in a rolling mode, a resistor arranged at one end of the rolling drum and a rollback spring arranged at the other end of the rolling drum. The spring free end of the rollback spring is connected with the rolling drum and rotates along with rotating of the rolling drum, the connecting end of the rollback spring is connected to the support at the other end of the rolling drum, and the resistor comprises a threaded rod with a connecting part, a pipe sleeve rotatably connected to the connecting part in a sleeving mode, a friction piece arranged on the connecting part and located in front of the pressing end of the pipe sleeve, a nut connected to the threaded rod in a screwed mode and a spring connected to the threaded rod in a penetrated mode and located between the nut and the friction piece; and the connecting part of the resistor is connected to the support of one end of the rolling drum. Compared with the prior art, the roller shutter has the advantages that the roller shutter can be convenient to unroll and roll, and the length of the curtain unrolled by the roller shutter is controllable and accurate.