Hydrogels are promising candidate materials for biomedical applications because of their similarities to human tissue. However, precise and independent control of their physical properties is difficult because hydrogels inevitably have inhomogeneous polymer networks. In particular, precise and independent control of biodegradability, which is one of the most important characteristics for biomaterials, has never been achieved. In order to control the degradability, we invented a novel hydrogel based on the concept of Tetra-PEG gel, which has an. extremely homogeneous polymer network. The degradability was precisely controlled, and the degradation time was predicted by a universal equation with one intrinsic parameter: the degradation rate constant.