Adhesive strength shows temperature and rate dependencies that reflect viscoelastic properties of an adhesive. Similarly, a critical strain energy release rate is expected to show temperature and rate dependencies because deformation and fracture of the adhesive occur at the time of the measurement of the strain energy release rate, which is a kind of fracture mechanical parameter for adhesive joints. In this study, the critical strain energy release rate (G(IIC)) of a plane-shear mode was measured over a wide range of temperatures and rates, and then a master curve was obtained by applying the temperature-rate superposition principle to the obtained data. The relation between G(IIC) and adhesive shear strength was also investigated.