A walking training system, a harness, and an operation method capable of performing training effectively are provided. A walking training system according to an embodiment includes a harness attached to a trainee's trunk and a pulling unit configured to apply a pulling force to the harness, the harness includes a frame fixed to the trainee's trunk, an attaching member to which the pulling unit is attached, and a guide mechanism configured to enable a position of the frame relative to the attaching member to be variable in an up/down direction.