An expander harness for walking pets on a leash, comprising a back part (3) equipped with a lining (2). A limiting element (10) is threaded through the leash connector (16) on the back part (3), which is fixed to the lining (2) by a limiting element fixing point (12) crossing the intersection of the axis line (9) and a separating axis line (9a).
The leash connector (16) on one side of the separating axis line (9a), and the at least one shoulder part connecting element (18) on the other side of the separating axis line (9a), are elastically displaced in the direction opposite to each other, moving away from each other to the extent of the stretching of the elastic element (11) threaded through the leash connector (16), extending between the leash connector (16) and the limiting element fixing point (12), and that of the shoulder part elastic element (21) threaded through the shoulder part connecting element (18).