Disclosed is a robotic orthosis for a lower extremity for gait rehabilitation training, comprising a knee stretching member which is provided to be installable on the knee so as to enable the knee joint to be stretched in a swing phase and enable a state in which the knee is stretched to be maintained in a stance phase. The knee stretching member comprises: a knee sleeve surrounding the knee joint; and a knee supporting chamber which is mounted so as to be connected to the knee sleeve, and which, when air is introduced therein and is inflated in the swing phase, enables the knee to be stretched by supporting the knee joint, and enables the state in which the knee is stretched to be maintained in the stance phase.
