Researches of soft materials are gradually expanding recently. Soft material is the material having Young’s modulus less than 100 MPa, which can be flexibly deformed when an external force is applied, and has a very large elastic limit. Taking the advantages of the flexibility and stretchability, soft materials can be applied extensively in the field of flexible devices, soft biomaterials, soft robots, etc. Our research groups are dealing with soft material-based mechanical metamaterials, and soft-based flexible devices. The development of our soft materials with extraordinary mechanical and electrical properties is expected to contribute greatly to the economic and technological aspects of the soft materials and devices industry.