Polymer gels formed from A-B type of coupling reaction were investigated vigorously as a "model network" because the mesh size of the network was defined by the size and shape of the building blocks. However, the formation of these networks has an inherent difficulty in homogeneous mixing of mutually reactive building blocks, leading to the formation of inhomogeneous network structures. Recently, we have designed and fabricated the Tetra-PEG gel by combining two well-defined symmetrical tetra-arm polymers of the same size. Although this gel was formed by simply mixing two polymer solutions, the structure was extremely homogeneous. In this study, we investigated the gelation kinetics of Tetra-PEG gel in detail. The reaction kinetics corresponded well with the theoretical prediction, suggesting the homogeneous reacting system. This homogeneous reacting system may contribute to the homogeneous network structure of Tetra-PEG gel.