Exoskeletal robots, i.e., robots integrated with the human body, have been developed since the 1960s, but these were initially not effective. Recently, these robots have been actively developed as wearable robots, with a wide range of practical applications expected for them in the near future. In this chapter, as an important feature of wearable robots, we explain the force interaction conditions between the wearer and the wearable robot for each application. As an example, we introduce the HAL (Hybrid Assistive Limb) robot suit and present, in particular, the interaction technologies and several clinical case studies related to it.