The invention relates to an orthosis (10) for supporting an arm of a person and to a method for the placement of an orthosis. Said orthosis comprises a securing device (11) for securing the orthosis to the torso of the person and a positioning device (12) for supporting and fixing the arm, in particular the forearm, elbow, and/or upper arm, relative to the shoulder corresponding to the arm of the person. The positioning device is maintained by the securing device, and the securing device comprises an abdominal strap device (13) and a shoulder strap device (14). The abdominal strap device surrounds the torso on a transversal plane when the orthosis is placed on a person, and the shoulder strap device runs over the shoulder further away from the arm of the person. The shoulder strap device comprises a shoulder strap (23) and a chest strap (22) which is connected to the shoulder strap, said straps being hinged to a distal end (24) and a proximal end (29) of the positioning device and to a ventral portion (26) of the abdominal strap device.
