As the world propagates toward the aging society, aging-related illnesses have been gaining attention. Among them, a lumbar degenerative flat back is a common condition caused by a decline in back muscle strength with aging and its symptoms include severe lower back pain, further restricting people from performing various activities in our daily lives. Although various commercially available wearable robots can assist weakened back muscles, the wearables required either bulky and rigid structures (active wearables) or tended to constrain users’ motion (passive wearables). Additionally, the spinal disorder of patients with lumbar degenerative flat back has not been studied during the design process of wearable robots. To address these problems, we propose a human-inspired spinal assistive robot (SpiRo) with a twisted string actuator (TSA) and a flat-back alleviation mechanism (FAM). By assisting the degenerated muscles by TSA, while aiding spinal disorder by FAM, we have taken the synergistic effect of using both components. In the future, we aim to further validate the effectiveness of the proposed SpiRo by organizing a long-term medical treatment for actual by collaborating with medical departments.